LETTER IV.

_INJURIES CAUSED BY INSECTS._

DIRECT INJURIES.

In the letter which I devoted to the defence of Entomology, I gave you reason to expect, more effectually to obviate the objection drawn from the supposed insignificance of insects, that I should enter largely into the question of their importance to us both as instruments of good and evil. This I shall now attempt; and, as I wish to leave upon your mind a pleasant impression with respect to my favourites, I shall begin with the last of these subjects--the _injury_ which they do to us.

The Almighty ordains various instruments for the punishment of offending nations: sometimes he breaks them to pieces with the iron rod of war; at others the elements are let loose against them; earthquakes and floods of fire, at his word, bring sudden destruction upon them; seasons unfriendly to vegetation threaten them with famine; the blight and mildew realize these threats; and often, the more to manifest and glorify his power, he employs means, at first sight, apparently the most insignificant and inadequate to effect their ruin; the numerous tribes of _insects_ are his armies[106], marshalled by him, and by his irresistible command impelled to the work of destruction: where he directs them they lay waste the earth, and famine and the pestilence often follow in their train.

The generality of mankind overlook or disregard these powerful, because minute, dispensers of punishment; seldom considering in how many ways their welfare is affected by them: but the fact is certain, that should it please God to give them a general commission against us, and should he excite them to attack, at the same time, our bodies, our clothing, our houses, our cattle, and the produce of our fields and gardens, we should soon be reduced, in every possible respect, to a state of extreme wretchedness; the prey of the most filthy and disgusting diseases, divested of a covering, unsheltered, except by caves and dungeons, from the inclemency of the seasons, exposed to all the extremities of want and famine; and in the end, as Sir Joseph Banks, speaking on this subject, has well observed[107], driven with all the larger animals from the face of the earth. You may smile, perhaps, and think this a high-coloured picture, but you will recollect--I am not stating the mischiefs that insects commonly do, but what they would do according to all probability, if certain counter-checks restraining them within due limits had not been put in action; and which they actually do, as you will see, in particular cases, when those counter-checks are diminished or removed.

Insects may be said, without hyperbole, to have established a kind of universal empire over the earth and its inhabitants. This is principally conspicuous in the injuries which they occasion, for nothing in nature that possesses or has possessed animal or vegetable life, is safe from their inroads. Neither the cunning of the fox, nor the swiftness of the horse or deer, nor the strength of the buffalo, nor the ferocity of the lion or tiger, nor the armour of the rhinoceros, nor the giant bulk or sagacity of the elephant, nor even the authority of imperial man, who boasts himself to be the lord of all, can secure them from becoming a prey to these despised beings. The air affords no protection to the birds, nor the water to the fish; insects pursue them all to their most secret conclaves and strongest citadels, and compel them to submit to their sway. Flora's empire is still more exposed to their cruel domination and ravages; and there is scarcely one of her innumerable subjects, from the oak, the glory of the forest, to the most minute lichen that grows upon its trunk, that is not destined to be the food of these next to nonentities in our estimation. And when life departs from man, the inferior animals, or vegetables, they become universally, sooner or later, the inheritance of insects.

I shall principally bespeak your attention to the injuries in question as they affect ourselves. These may be divided into direct and indirect. By _direct_ injuries I mean every species of attack upon our own persons, and by _indirect_, such as are made upon our property. To the former of these I shall confine myself in the present letter.

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Insects, as to their _direct_ attacks upon us, may be arranged in three principal classes. Those, namely, which seek to make us their food; those whose object is to prevent or revenge an injury which they either fear, or have received from us; and those which indeed offer us no violence, but yet incommode us extremely in other ways.

I hope I shall not too much offend your delicacy if I begin the first class of our insect assailants with a very disgusting genus, which Providence seems to have created to punish inattention to personal cleanliness. But though this pest of man must not be wholly passed over, yet, since it is unfortunately too well known, it will not be at all necessary for me to enlarge upon its history. I shall only mention one fact which shows the astonishingly rapid increase of these animals, where they have once gotten possession. It is a vulgar notion, that a louse in twenty-four hours may see two generations; but this is rather overshooting the mark. Leeuwenhoek, whose love for science overcame the nausea that such creatures are apt to excite, proves that their nits or eggs are not hatched till the eighth day after they are laid, and that they do not themselves commence laying before they are a month old. He ascertained, however, that a single female louse may, in eight weeks, witness the birth of five thousand descendants[108]. You remember how wolves were extirpated from this country, but perhaps never suspected any monarch of imposing a tribute of _lice_ upon his subjects. Yet we are gravely told that in Mexico and Peru such a _poll_-tax was exacted, and that bags full of these treasures were found in the palace of Montezuma[109]!!! Were our own taxes paid in such coin, what little grumbling would there be!

Two other species of this genus, besides the common louse, are, in this country, parasites upon the human body----But already I seem to hear you exclaim, "Why dwell so long on creatures so odious and nauseating, whose injuries are confined to the _profanum vulgus_? Leave them therefore to the canaille--they are nothing to us." Not so fast, my friend--recollect what historians and other writers have recorded concerning the _Phthiriasis_ or pedicular disease, and you must own that, for the quelling of human pride, and to pull down the high conceits of mortal man, this most loathsome of all maladies, or one equally disgusting, has been the inheritance of the rich, the wise, the noble, and the mighty; and in the list of those that have fallen victims to it, you will find poets, philosophers, prelates, princes, kings, and emperors. It seems more particularly to have been a judgement of God upon oppression and tyranny, whether civil or religious. Thus the inhuman Pheretima mentioned by Herodotus, Antiochus Epiphanes, the Dictator Sylla, the two Herods, the Emperor Maximin, and, not to mention more, the great persecutor of the Protestants, Philip the Second, were carried off by it.

I say by this malady, _or one equally disgusting_, because it is not by any means certain, though some learned men have so supposed, that all these instances, and others of a similar nature, standing also upon record, are to be referred to the same specific cause; since there is very sufficient reason for thinking that at least _three_ different descriptions of insects are concerned in the various cases that have been handed down to us under the common name of _Phthiriasis_. As the subject of maladies connected with insects, or produced by them, is both curious and interesting, although no writer, that I am aware of, has given it full consideration, and at the same time falls in with my general design, I hope you will not regard me as guilty of presumption, and of intruding into the province of medical men, if I enter rather largely into it, and state to you the reasons that have induced me to embrace the above hypothesis, leaving you full liberty to reject it if you do not find it consonant to reason and fact. The three kinds of insects to which I allude, as concerned in cases that have been deemed Phthiriasis, are lice (_Pediculi_, L.) mites (_Acari_, L.), and _Larvæ_ in general.

As far as the habits of the genus _Pediculus_, whether inhabiting man or the inferior animals, are at present known, it does not appear, from any well ascertained fact, that the species belonging to it are ever _subcutaneous_. For this observation, as far as it relates to man, I can produce the highest medical authority. "The louse feeds on the surface of the skin," says the learned Dr. Mead in his _Medica Sacra_; and Dr. Willan, in his palmary work on _Cutaneous Diseases_, remarks with respect to the body-louse, "that the nits, or eggs, are deposited on the small hairs of the skin," and that "the animals are found on the skin, or on the linen, and not under the cuticle, as some authors have represented." And he further observes, that "many marvellous stories are related by Forestus, Schenkius and others respecting lice bred under the skin, and discharged in swarms from abscesses, strumous ulcers, and vesications. The mode in which Pediculi are generated being now so well ascertained, no credit can be given to these accounts." Thus far this great man, who however supposes (in which opinion Dr. Bateman concurs with him) that the authors to whom he alludes had mistaken for lice some other species of insects, which are not unfrequently found in putrefactive sores.

If these observations be allowed their due weight, it will follow, that a disease produced by animals residing under the cuticle cannot be a true Phthiriasis, and therefore the death of the poet Alcman, and of Pherecydes Syrius the philosopher, mentioned by Aristotle, must have been occasioned by some other kind of insect. For, speaking of the lice to which he attributes these catastrophes, he says that "they are produced in the flesh in small pustule-like tumours, which have no pus, and from which when punctured, they issue[110]." For the same reason, the disorder which Dr. Heberden has described in his _Commentaries_, from the communications of Sir E. Wilmot, under the name of _Morbus pedicularis_, must also be a different disease, since, with Aristotle, he likewise represents the insects as inhabiting tumours, from which they may be extracted when opened by a needle. He says, indeed, that in every respect they resemble the common lice, except in being whiter; but medical men, who were not at the same time entomologists, might easily mistake an Acarus for a Pediculus[111].

Dr. Willan, in one case of _Prurigo senilis_, observed a number of small insects on the patient's skin and linen. They were quick in their motion, and so minute that it required some attention to discover them. He took them at first for small Pediculi; but under a lens they appeared to him rather to be a nondescript species of Pulex[112]; yet the figure he gives has not the slightest likeness to the latter genus, while it bears a striking resemblance to the former. It is not clear whether his draughtsman meant to represent the insect with six or with eight legs: if it had only six, it was probably a Pediculus; but if it had eight, it would form a new genus between the _Acarina_ and the hexapod _Aptera_. Dr. Bateman, in reply to some queries put to him, at my request, by our common and lamented friend Dr. Reeve, relates that he understood from Dr. Willan, in conversation, that the insect in question jumped in its motion. This circumstance he regards as conclusive against its being a Pediculus; but such a consequence does not necessarily follow, since it not seldom happens that insects of the same tribe or genus either have or have not this faculty; for instance, compare _Scirtes_ with _Cyphon_, small beetles, and _Acarus Scabiei_ with other _Acari_[113].

Dr. Willan has quoted with approbation two cases from Amatus Lusitanus, which he seems to think correctly described as Phthiriasis. In one of them, however, which terminated fatally, the circumstances seem rather hyperbolically stated--I mean, where it is said that two black servants had no other employment than carrying baskets full of these insects to the sea!! Perhaps you will think I draw largely upon your credulity if I call upon you to believe this; I shall therefore leave you to act as you please.--Thus much for pure Phthiriasis, which term ought to be confined to maladies produced by _lice_. I shall only further observe, that as many species as exist of these, which are the causes of disease, so many kinds of Phthiriasis will there be.

_Acari_, or mites, are the next insect sources of disease in the human species, and that not of one, but probably of many kinds both local and general. They are distinguished from Pediculi not only by their form, but also often by their situation, since they frequently establish themselves under the cuticle. With respect to local disorders, Dr. Adams conjectures that Acari may be the cause of certain cases of _Ophthalmia_. Sir J. Banks, in a letter to that gentleman, relates that some seamen belonging to the Endeavour brig, being tormented with a severe itching round the extremities of the eyelids, one of them was cured by an Otaheitan woman, who with two small splinters of bamboo extracted from between the _cilia_ abundance of very minute lice, which were scarcely visible without a lens, though their motion, when laid on the thumb, was distinctly perceived. These insects were probably synonymous with the _Ciron des paupières_ of Sauvages[114].--Le Jeune, a French physician quoted in Mouffet, describes a case, in which what seems a different species, since he calls them rather large, infested the white of the eye, exciting an intolerable itching[115].--Dr. Mead, from the _German Ephemerides_, gives an account of a woman suckling her child, from whose breast proceeded very minute vermicles[116]. These were probably mites, and perhaps that species, which, from its feeding upon milk, Linné denominates _Acarus Lactis_. The great author last mentioned describes an insect, a native of America, under the name of _Pediculus Ricinoides_, which, upon the authority of Rolander, he informs us, gets into the feet of people as they walk, sucks their blood, oviposits[117] in them, and so occasions very dangerous ulcers. It would be an Acarus, he observes, but it has only six legs. Now Hermann affirms, that some species of _Trombidium_ (a genus separated by Fabricius from _Acarus_) have in no state more than six legs[118]. Others of the tribe of _Acarina_, and the insect in question amongst the rest, may be similarly circumstanced; or those that Rolander examined might have been larvæ, which in this tribe are usually hexapods.

Linné appears to have been of opinion that many contagious diseases are caused by mites[119]. How far he was justified in this opinion I shall not here inquire; facts alone can decide the question, and observations made by men acquainted with Entomology as well as the science of diseases. Considerable deference and attention, however, are certainly due to the sentiments of so great a naturalist, in whom these necessary qualifications were united in no common degree. With respect to the dysentery and the itch, he affirms that this had been manifested to his eyes. You will wish probably to know the arguments that may be adduced in confirmation of this opinion; I will therefore endeavour to satisfy you as well as I am able. The following history given by Linné seems to prove the dysentery connected with these animals.

Rolander, a student in Entomology, while he resided in the house of the illustrious Swede, was attacked by the disease in question, which quickly gave way to the usual remedies. Eight days after, it returned again, and was as before soon removed. A third time, at the end of the same period, he was seized with it. All the while he had been living like the rest of the family, who had nevertheless escaped. This, of course, occasioned no little inquiry into the cause of what had happened. Linné, aware that Bartholinus had attributed the dysentery to _insects_, which he professed to have seen, recommended it to his pupil to examine his feces. Rolander, following this advice, discovered in them innumerable animalcules, which upon a close examination proved to be mites. It was next a question how he alone came to be singled out by them; and thus he accounts for it. It was his habit not to drink at his meals; but in the night, growing thirsty, he often sipped some liquid out of a vessel made of juniper wood. Inspecting this very narrowly, he observed, in the chinks between the ribs, a white line, which, when viewed under a lens, he found to consist of innumerable mites, precisely the same with those that he had voided. Various experiments were tried with them, and a preparation of rhubarb was found to destroy them most effectually. He afterwards discovered them in vessels containing acids, and often under the bung of casks[120]. In the instance here recorded, the dysentery, or diarrhœa, was evidently produced by a species of mite, which Linné hence called _Acarus Dysenteriæ_; but it would be going too far, I apprehend, to assert that they are invariably the cause of that disease.

That _Scabies_, or the itch, is occasioned by a mite, is not a doctrine peculiar to the moderns. Mouffet mentions Abinzoar, called also Avenzoar, a celebrated Hispano-Arabian physician of Seville, who flourished in the twelfth century, as the most ancient author that notices it. He calls these mites little lice that creep under the skin of the hands, legs, and feet, exciting pustules full of fluid[121]. Joubert, quoted by the same author, describes them under the name of _Sirones_, as always being concealed beneath the epidermis, under which they creep like moles, gnawing it, and causing a most troublesome itching. It appears that Mouffet, or whoever was the author of that part of the _Theatrum Insectorum_, was himself also well acquainted with these animals, since he remarks that their habitation is not in the pustule but near it: a remark afterwards confirmed by Linné[122], and more recently by Dr. Adams[123]. In common with the former of these authors, Mouffet further notices the effect of warmth upon them in exciting motion[124]. Our intelligent countryman also observes that they cannot be Pediculi, since they live under the cuticle, which lice never do[125]. In the epistle dedicatory, the editor speaks also of them as living in burrows which they have excavated in the skin near a lake of water; from which if they be extracted with a needle and put upon the nail, they show in the sun their red head and the feet with which they walk[126]. And to close my _veteran_ authorities, Junius thus explains the word Acarus, as I find him quoted in Gouldman's useful dictionary, "A small worm, which eats under the skin, and makes burrows in itching hands[127]."

In more modern times, microscopical figures have been added to descriptions of the insect. Bonomo first furnished this valuable species of elucidation. His figures, however, which are copied by Baker in his work on the microscope, are far from accurate[128]. Those of De Geer and Dr. Adams are much more satisfactory, and mutually confirm each other[129]. From them it is evident that the same insect inhabits the scabies of Sweden and Madeira. Dr. Bateman, in the letter before alluded to, informs his correspondent, that he had seen that from Madeira, and gives it as his opinion, that there cannot be a doubt of the existence of an _Acarus Scabiei_; an opinion which he repeats in his late work on _Cutaneous Diseases_; and which, according to Hermann[130], has been also rendered unquestionable by Wichmann in his _Etiologie de la Gale_ (Hanovre 1786), a work I have not had an opportunity of consulting. From all this we may regard the point as so far settled, that an animal of this kind exists at least as an occasional concomitant of scabies.

This fact being ascertained, a more complex inquiry remains, which branches out into two distinct questions. Is scabies always produced by these insects? Or, if this be not the case, Is the _animate_ scabies a distinct disease from the _inanimate_?

It is very remarkable that Linné, a physician as well as a naturalist; and De Geer, one of the most accurate observers that ever existed; should both assign the insect in question as the undoubted cause of the _common_ scabies of their country; the one applying to the disease he was speaking of the epithet of _communissima_, and observing the fact to be notorious, (_cuique liquet_,) and the other designating it by its well known French name "_La Gale_[131]." And is it not equally remarkable that such men as John Hunter, Dr. Heberden, Dr. Bateman, Dr. Adams, and Mr. Baker, should never, in this country, have been able to meet with it? Did it indeed exist in our common scabies, it seems impossible that it could have escaped the observation of the two last of these gentlemen; Dr. Adams being so well qualified to detect it from his observations in Madeira, and Mr. Baker from his expertness in microscopical researches. Dr. Bateman, in the letter above quoted, says, "I have hunted it with a good magnifier, in many cases of itch, both in and near the pustules, and in the red streaks or furrows, but always without success." In his work on _Cutaneous Diseases_ he tells us, however, that he has seen it, in one instance, when it had been taken from the diseased surface by another practitioner. And though Dr. Willan in his book speaks of the Acarus as the concomitant of this disease, yet his learned friend just mentioned observes, that he admitted that it was not to be found in ordinary cases, and indeed never seemed to have made up his mind upon the subject. When I was at Norwich in 1812, Dr. Reeve very kindly accompanied me to the House of Industry there, to examine a patient whose body was very full of the pustules of this disorder; but though we used a good magnifier, we could discover nothing like an insect. I must observe, however, that our examination was made in December, in severe weather, when the cold might, perhaps, render the animal torpid, and less easy to be discovered.

From the above facts it seems fair to infer that this animal is not invariably the cause of scabies, but that there are cases with which it has no connexion. Now, from this inference, would not another also follow, that the disease produced by the insect is specifically distinct from that in which it cannot be found? Sauvages and Dr. Adams are both of this opinion[132], the former assigning to it the trivial name of _vermicularis_; and the latter proving, by very satisfactory arguments, that it is different from the other. If they were both _animate_ diseases, but derived from two distinct species of animals, (for it seems not impossible that even our common itch may be caused by a mite more minute than the other, and so more difficult to find,) they would properly be considered as distinct species; much more, therefore, if one be _animate_ and the other _inanimate_. Nay this, I should think, would lead to a doubt whether even their _genus_ were the same. I shall dismiss this part of my subject with the mention of a discovery of Dr. Adams, which seems to have escaped both Linné and De Geer--that the _Acarus Scabiei_ is endowed with the faculty of leaping; (in this respect resembling the insect found by Willan in _Prurigo senilis_ mentioned above;) for which purpose its four posterior thighs are incrassated[133].

But besides these _Acarine_ diseases, there seems to be one (unless with Linné we regard the plague as of this class[134]) more fearful and fatal than them all. You will, perhaps, conjecture I am speaking of that described by Aristotle and Sir E. Wilmot as the Phthiriasis, and your conjecture will be right. But some think, and those men of merited celebrity, that _mites_ have nothing to do in these and similar cases, for that _maggots_ were the parasites mistaken for lice. This, from the passage above quoted, appears to have been Dr. Willan's opinion, to which, in the letter so often referred to, Dr. Bateman subscribes; adding as a reason for excluding mites from being concerned, that "they are too minute, and never have been seen in such numbers as to be mistaken for lice." But both vary in size, some of the former being larger than some of the latter. And allowing them to be ever so minute, yet when they issue in swarms, as mites from a cheese, they would be very visible, were it only from their motion. Besides, as they are furnished with legs, their motions resemble those of lice infinitely more than do the contortions of maggots. So that a mite would be deemed a louse much sooner by an unentomological observer than would a maggot. Whether mites have ever been seen in such numbers as to be mistaken for lice, is the point in question; and therefore, by itself, cannot be admitted for a valid argument. Though _Acarus Scabiei_ does not appear to swarm in ordinary cases, yet this is certainly no reason why other species may not do so. Where it has once made a settlement, how incredibly, and in how short a space of time, does the _Siro_ or cheese-mite multiply! _Acarus Destructor_ and many other species are equally rapid in their increase.--Millions of lice are said by Lafontaine, whom Hermann calls a very exact describer, to show themselves in _Plica polonica_, on the third day of the disease[135]; but whether the last-mentioned author be correct in thinking it more probable that they are mites[136], I have not the means of judging.

I shall now produce two instances where mites were evidently concerned. Dr. Mead, from the _German Ephemerides_, relates the miserable case of a French nobleman, from whose eyes, nostrils, mouth, and urinary passage animalcules of a red colour, and excessively minute, broke forth day and night, attended by the most horrible and excruciating pains, and at length occasioned his death. The account further says, that they were produced from his corrupted blood. This was probably a fancy originating in their red colour: but the whole history, whether we consider the size and colour of the animals, or the places from which they issue, is inapplicable to _larvæ_ or maggots, and agrees very well with _mites_, some of which, particularly _Leptus autumnalis_, are of a bright red colour. The other case, and a very similar one, is that recorded by Mouffet of Lady Penruddock; concerning whom he expressly tells us, that Acari swarmed in every part of her body--her head, eyes, nose, lips, gums, the soles of her feet, &c., tormenting her day and night, till, in spite of every remedy, all the flesh of her body being consumed, she was at length relieved by death from this terrible state of suffering. Mouffet attributes her disease to the _Acarus Scabiei_; but from the symptoms and fatal result it seems to have been a different and much more terrific animal. He supposes, in this instance, the insect to have been generated by drinking goat's milk too copiously. This, if correct, would lead to a conjecture that it might have been the _A. Lactis_, L.

These cases I hope will satisfy you that mites, as well as lice, are the cause of diseases in the human frame. This, indeed, as has been before observed, is allowed on all hands with respect to that of the itch; and it is, certainly, not more improbable that man should be exposed to the attack of several species of this genus, than that three or four kinds of Pediculus should infest him. If you are convinced by what I have written, you will concur with me in thinking that the one are as much entitled to give their name to the disease which they produce as the other; and the term _Acariasis_, by which, with due deference to medical men, I propose to distinguish generically all acarine diseases, will not be refused its place amongst your _Genera Morborum_.

I shall now proceed to the remaining class of diseases mistaken for Phthiriasis; those, namely, which are produced by _larvæ_. There are two terms employed by ancient authors, _Eulæ_ (Ευλαι) and _Scolex_ (Σκωληξ), which seem properly to denote larvæ; but there is often such a want of precision in the language of writers unacquainted with Natural History, that it is very difficult to make out what objects they mean; and expressions which, strictly taken, should be understood of larvæ, may probably sometimes have been used to denote the cause of either the pedicular or acarine disease. _Eulæ_, which term, though given by Hesychius as synonymous with _Scolex_, is by Plutarch used as of different import[137], seems properly to mean those larvæ which are generated in dead carcases, at least so Homer has more than once applied it[138]: it is therefore a word of a much more restricted sense than _Scolex_, which probably belongs to the larvæ of every order of insects; for so Aristotle employs it, when he says that all insects produce a _Scolex_, or are larviparous[139]. Yet when Homer compares Harpalion stretched dead upon the ground to a _Scolex_[140], it should seem as if he used the word for an earth-worm, which Aristotle commonly calls by a figurative periphrasis, "Entrails of the earth[141]." In the Holy Scriptures this word is used to signify larvæ which prey upon and are the torment of living bodies[142]. It may on this account, perhaps, be regarded as generally meaning such larvæ, to whatever order or genus they belong.

Dr. Mead, therefore, is most probably right when he considers the disease stated by the ancients to be caused by _Eulæ_ or _Scoleches_, commonly translated worms, as distinct from Phthiriasis; and if so, the inhuman Pheretima, who swarmed with _Eulæ_, and Herod Agrippa, who was eaten of _Scoleches_[143], were probably neither of them destroyed either by Pediculi or Acari, but by larvæ or maggots. And when Galen prescribed a remedy for ulcers inhabited by _Scoleches_, observing that animals similar to those generated by putrid substances are often found in abscesses, he probably meant the same thing. The proper appellation of this genus of diseases would be _Scolechiasis_.

This dissertation may perhaps appear to you rather prolix and tedious: yet to settle the meaning of terms is of the first importance. To inquire what ancient writers intended by the words which they employ, and whether such as have been usually regarded as synonymous are really so, may often furnish us with a clue to some useful or interesting truth; and not seldom enable us to rescue their reputation from much of the censure which has been inconsiderately cast upon it. Because they did not know every thing, or so much as we do, we are too apt to think that they knew nothing. That they fell into very considerable errors, especially in subjects connected with Natural History, cannot be denied; but then it ought to be considered that they possessed scarcely any of those advantages by which we are enabled to penetrate into nature's secrets. The want of the microscope alone was an effectual bar to their progress in this branch of science. Yet, in some instances, when they took a general view of a subject, they appear to have had very correct ideas. This observation particularly applies to the philosopher of Stagyra, whose mighty mind and lyncean eye, in spite of those mists of prejudice and fable that enveloped the age in which he lived, enabled him in part to pierce through the gloom, and comprehend and behold the fair outline that gives symmetry, grace and beauty to the whole of nature's form, though he mistook, or was not able to trace out, her less prominent features and minor lineaments.

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It is now time to return from this long digression, which however is closely connected with the subject of this letter, to the point from which I deviated. Taking my leave of the disgusting animals which gave rise to it, I proceed to call your attention to another of our pygmy tormentors, (_Pulex irritans_,) which, in the opinion of some, seems to have been regarded as an agreeable rather than a repulsive object. "Dear miss," said a lively old lady to a friend of mine, (who had the misfortune to be confined to her bed by a broken limb, and was complaining that the fleas tormented her,) "don't you like _fleas_? Well, I think they are the prettiest little merry things in the world.--I never saw a dull flea in all my life." The celebrated Willughby kept a favourite flea, which used at stated times to be admitted to suck the palm of his hand; and enjoyed this privilege for three months, when the cold killed it. And Dr. Townson, from the encomium which he bestows upon these vigilant little vaulters, as supplying the place of an alarum and driving us from the bed of sloth, should seem to have regarded them with feelings much more complacent than those of Dr. Clarke and his friends, when their hopes of passing "one night free from the attacks of vermin" were changed into despair by the information of the laughing Sheik, that "the king of the fleas held his court at Tiberias:" or than those of MM. Lewis and Clarke, who found them more tormenting than all the other plagues of the Missouri country, where they sometimes compel even the natives to shift their quarters. If you unhappily view them in this unfavourable light, and have found ordinary methods unavailing for ridding yourself of these unbidden guests; I can furnish you with a _probatum est_ recipe, which the first-mentioned traveller tells us the Hungarian shepherds (who seem to have been stupidly insensible to their value as alarums) find completely effectual to put to flight these insects and their neighbours the lice. This is not, as you may be tempted to think, by a remarkable attention to cleanliness.--Quite the reverse.--They grease their linen with hog's lard, and thus render themselves disgusting even to fleas! If this does not satisfy, I have another recipe in store for you. You may shoot at them with a cannon, as report says did Christina queen of Sweden, whose piece of artillery, of Lilliputian calibre, which was employed in this warfare, is still exhibited in the arsenal of Stockholm[144]. But, seriously, if you wish for an effectual remedy, that prescribed by old Tusser, in the following lines, will answer your purpose:

"While wormwood hath seed, get a handfull or twaine, To save against March, to make flea to refraine: Where chamber is sweeped, and wormwood is strown, No flea for his life dare abide to be known."

To this genus belongs an insect, abundant in the West Indies and South America, the attacks of which are infinitely more serious than those of the common flea. You will readily conjecture that I am speaking of the celebrated _Chigoe_ or _Jiggers_, called also _Nigua_, _Tungua_, and _Pique_[145], (_Pulex penetrans_,) one of the direst personal pests with which the sins of man have been visited. All disputes concerning the genus of this insect would have been settled long before Swartz's time, (who first gave a satisfactory description and figure of it, proving it to be a _Pulex_, as has been observed above[146],) had success attended the patriotic attempt of the Capuchin friar recorded by Walton in his _History of St. Domingo_, who brought away with him from that island a colony of these animals, which he permitted to establish themselves in one of his feet; but unfortunately for himself, and for science, the foot intrusted with the precious deposit mortified, was obliged to be amputated, and with all its inhabitants committed to the waves. According to Ulloa, and his opinion is confirmed by Jussieu, there are two South American species of this mischievous insect. It is described as generally attacking the feet and legs[147], getting, without being felt, between the skin and the flesh, usually under the nails of the toes, where it nidificates and lays its eggs; and if timely attention be not paid to it, which, as it occasions no other uneasiness than itching, (the sensation at first, I am assured, is rather pleasing than otherwise,) is sometimes neglected, it multiplies to such a degree, as to be attended by the most fatal consequences, often, as in the above instance, rendering amputation necessary, and sometimes causing death[148]. The female slaves in the West Indies are frequently employed to extract these pests, which they do with uncommon dexterity. Yarico, so celebrated in prose and verse, performed this kind office for honest Ligon, who says, in his _History of Barbadoes_, "I have had ten (Chegoes) taken out of my feet in a morning, by the most unfortunate Yarico, an Indian woman[149]." Humboldt observes, "that the whites born in the torrid zone walk barefoot with impunity in the same apartment where a European recently landed is exposed to the attack of this animal. The _Nigua_ therefore distinguishes what the most delicate chemical analysis could not distinguish, the cellular membrane and blood of a European from those of a creole white[150]."

You have already, perhaps, been satiated with the account before given of our enemies of the _Acarus_ tribe: there are a few, however, which I could not with propriety introduce there, as they do not take up their abode and breed in us, which nevertheless annoy us considerably. One of these is a hexapod so minute, that, were it not for the uncommon brilliancy of its colour, which is the most vivid crimson that can be conceived, it would be quite invisible. It is known by the name of the harvest-bug, (_Leptus autumnalis_,) and is so called, I imagine, from its attacking the legs of the labourers employed in the harvest, in the flesh of which it buries itself at the root of the hairs, producing intolerable itching, attended by inflammation and considerable tumours, and sometimes even occasioning fevers[151].--A similar insect is found in Brazil, abounding in the rainy season, particularly during the gleams of sunshine, or fine days that intervene; as small as a point, and moving very fast. These animals get upon the linen and cover it in a moment; afterwards they insinuate themselves into the skin and occasion a most intolerable itching. They are with difficulty extracted, and leave behind them large livid tumours, which subside in a day or two. An insect very tormenting to the wood-cutters and the settlers on the Mosquito shore and the bay of Honduras, and called by them _the doctor_, is thought to be synonymous with this[152].--More serious consequences have been known to follow the bite of another mite related to the above, if not the same species, common in Martinique, and called there the _Bête rouge_. When our soldiers in camp were attacked by this animal, dangerous ulcers succeeded the symptoms just mentioned, which, in several cases, became so bad, that the limb affected was obliged to be taken off[153].

I was once collecting insects in Norwood, near London, when my hands were covered by a number of small hungry ticks, which were so greedy after blood, that they penetrated deep into my flesh, giving me no little pain; and it was not without difficulty that I extracted them. I suspect that this was the dog-tick (_Ixodes Ricinus_) which is often found on plants; but I am not certain, as I neglected to examine it, my attention at that time being almost wholly given to _Coleoptera_. Lyonnet seems to have been attacked, in one of his entomological excursions, by the same or a similar insect, which he broke, so firmly had it fixed itself, in endeavouring to extract it; and he was obliged to lay open the place lest an abscess should be formed[154]. But the worst of all the tick tribe is the American (_Ixodes americanus_) described by Professor Kalm. This insect, which is related to the preceding, is found in the woods of North America, and is equally an enemy to man and beast. They are there so infinitely numerous, that if you sit down upon the ground, or upon the trunk of a tree, or walk with naked feet or legs, they will cover you, and, plunging their serrated rostrum into the bare places of the body, begin to suck your blood, going deeper and deeper till they are half buried in the flesh. Though at first they occasion no uneasiness, when they have thus made good their settlement, they produce an intolerable itching, followed by acute pain and large tumours. It is now extremely difficult to extract them, the animal rather suffering itself to be pulled to pieces than let go its hold; so that the rostrum and head being often left in the wound, produce an inflammation and suppuration which render it deep and dangerous. These ticks are at first very small, sometimes scarcely visible, but by suction will swell themselves out till they are as big as the end of one's finger, when they often fall to the ground of themselves[155]. The serrated haustellum of the ticks, which, like the barbed sting of a bee, cannot be extracted unless the animal cooperates, is well worth your inspection; and the species which infests our dogs is so common that you will have no difficulty in procuring one for examination.

I have now introduced you to the principal insects of the _Aptera_ order of Linné, which, in spite of all his care and all his power, assail the lord of the creation, and make him their food. You will here, however, perhaps accuse me of omitting one very prominent annoyer of our comfort and repose, which you think belongs to this tribe--the bed-bug (_Cimex lectularius_). When you are a more practised entomologist, you will see clearly that this, though it has no wings, appertains to another order: nevertheless it may be introduced here without impropriety. Though now too common and well known, in this country it was formerly a rare insect. Had it not, two noble ladies, mentioned by Mouffet, would scarcely have been thrown into such an alarm by the appearance of bug-bites upon them; which, until their fears were dispelled by their physician, who happened also to be a naturalist, they considered as nothing less than symptoms of the plague. Being shown the living cause of their fright, their fears gave place to mirth and laughter[156]. Commerce, with many good things, has also introduced amongst us many great evils, of which noxious insects form no small part; and one of her worst presents were doubtless the disgusting animals now before us. They seem, indeed, as the above fact proves, to have been productive of greater alarm at first than mischief, at least if we may judge from the change of name which took place upon their becoming common. Their original English name was _Chinche_ or _Wall-louse_[157]; and the term _Bug_, which is a Celtic word, signifying a ghost or goblin, was applied to them after Ray's time, most probably because they were considered as "terrors by night[158]." But however horrible bugs may have been in the estimation of some, or nauseating in that of others, many of the good people of London seem to regard them with the greatest apathy, and take very little pains to get rid of them; not generally, however, it is to be hoped, to such an extent as the predecessor of a correspondent in Nicholson's _Journal_, who found his house so dreadfully infested by them, that it resembled the Banian hospital at Surat[159], all his endeavours to destroy them being at first in vain. And no wonder; for, as he learned from a neighbour, his predecessor would never suffer them to be disturbed or his bedsteads to be removed, till, in the end, they swarmed to an incredible degree, crawling up even the walls of his drawing-room; and after his death millions were found in his bed and chamber furniture[160].

The winged insects of the order to which the bed-bug belongs, often inflict very painful wounds.--I was once attacked by a small species, near _Cimex Nemorum_, L. (_Hylophila_, K.), which put me nearly to as much torture as the sting of a wasp. The water boatman (_Notonecta glauca_), an insect related to the _Cimicidæ_, which always swims upon its back, made me suffer still more severely, as if I had been burned, by the insertion of its rostrum; but the wound was not followed by any inflammation; and long before me Willughby had made the same discovery and observation[161]. St. Pierre, in his _Voyage to Mauritius_, mentions a species of bug found in that island, the bite of which is more venomous than the sting of a scorpion, and is succeeded by a tumour as big as the egg of a pigeon, which continues for four or five days. You are well acquainted with the history and properties of the _Raia Torpedo_ and _Gymnotus electricus_; but, I dare aver, have no idea that any _insect_ possesses their extraordinary powers.--Yet I can assure you, upon good authority, that _Reduvius serratus_, commonly known in the West Indies by the name of the wheel-bug, can, like them, communicate an electric shock to the person whose flesh it touches. The late Major-general Davies, of the Royal Artillery, well known as a most accurate observer of nature and an indefatigable collector of her treasures, as well as a most admirable painter of them, once informed me, that when abroad, having taken up this animal and placed it upon his hand, it gave him a considerable shock, as if from an electric jar, with its legs, which he felt as high as his shoulders; and, dropping the creature, he observed six marks upon his hand where the six feet had stood.

You may now possibly think that I have nearly gone through the catalogue of our _personal_ assailants of the insect tribes. If such, however, is your expectation, I fear you will be disappointed, since I have many more, and some tremendous ones, to enumerate: but as a small compensation for such a detail of evils and injuries to which our species is exposed from foes seemingly so insignificant, and of acts of rebellion of the vilest and most despised of our subjects against our boasted supremacy, the objects to which I shall next call your attention are not, like most of our apterous enemies, calculated to excite disgust and nausea when we see them or speak of them; nor do they usually steal upon us during the silent hours of repose, (though I must except here the gnat or mosquito,) but are many of them very beautiful, and boldly make their attack upon us in open day, when we are best able to defend ourselves. Borne on rapid wings, wherever they find us, they endeavour to lay us under contribution, and the tribute they exact is our blood. Wonderful and various are the weapons that enable them to enforce their demand. What would you think of any large animal that should come to attack you with a tremendous apparatus of knives and lancets issuing from its mouth? Yet such are the instruments by means of which the fire-eyed and blood-thirsty horse-fly (_Tabanus_, L.) makes an incision in your flesh; and then, forming a siphon of them, often carries off many drops of your blood[162]. The pain they inflict, when they open a vein, is usually very acute. A fly of this kind not only occasioned Mr. Sheppard considerable pain by its bite, but also produced swelling and blackness round one eye; and the flesh of his cheek and chin was so enlarged from it as to hang down. And Mr. W. S. MacLeay thus describes to me the annoyance he suffered from one of them. "I went down the other day to the country, and was fairly driven out of it by the _Hæmatopota pluvialis_, which attacked me with such fury, that although I did not at last venture beyond the door without a veil, my face and hands were swelled to that degree as to be scarcely yet recovered from the effects of their venom. I was obliged on my return to town to stay two days at home. Whenever this insect bites me it has this effect, and I have never been able to discover any remedy for the torture it puts me to." In this country, however, the attacks of these flies are usually not frequent enough to make them more than a minor "misery of human life;" but the burning-fly (_brulot_) or sand-fly of America[163] and the West Indies, which seem to be the same insect, causes a much more intolerable anguish, which has been compared to what a red-hot needle or a spark of fire would occasion us to endure. Lambert, in his _Travels through Canada_, &c. says, "They are so very small as to be hardly perceptible in their attacks; and your forehead will be streaming with blood before you are sensible of being amongst them[164]."--Yet we have one species (_Stomoxys calcitrans_) alluded to in a former letter as so nearly resembling the common house-fly[165], which, though its oral instruments are to appearance not near so tremendous, is a much greater torment than the horse-fly. This little pest, I speak feelingly, incessantly interrupts our studies and comfort in showery weather, making us even stamp like the cattle by its attacks on our legs; and, if we drive it away ever so often, returning again and again to the charge. In Canada they are infinitely worse. "I have sat down to write," says Lambert, (who though he calls it the house-fly is evidently speaking of the Stomoxys,) "and have been obliged to throw away my pen in consequence of their irritating bite, which has obliged me every moment to raise my hand to my eyes, nose, mouth, and ears in constant succession. When I could no longer write, I began to read, and was always obliged to keep one hand constantly on the move towards my head. Sometimes in the course of a few minutes I would take half a dozen of my tormentors from my lips, between which I caught them just as they perched[166]."

The swallow-fly (_Craterina Hirundinis_[167]), whose natural food is the bird after which it is named, has been known to make its repast on the human species. One found its way into a bed of the Rev. R. Sheppard, where it first, for several nights, sorely annoyed a friend of his, and afterwards himself, without their suspecting the culprit. After a close search, however, it was discovered in the form of this fly, which, forsaking the nest of the swallow, had by some chance taken its station between the sheets, and thus glutted itself with the blood of man.--In travelling between Edam and Purmerend in North Holland (July 21, 1815), in an open vehicle, I was much teased by another bird-fly (_Ornithomyia avicularia_) (two individuals of which I caught) alighting upon my head, and inserting its rostrum into my flesh.--Mr. Sheppard remarks, as a reason for this dereliction of their appropriate food, that no sooner does life depart from the bird that these flies infest, than they immediately desert it and take flight, alighting upon the first living creature that they meet with; which if it be not a bird they soon quit, but, as it should seem from the above facts, not before they have made a trial how it will suit them as food.

But of all the insect-tormentors of man, none are so loudly and universally complained of as the species of the genus _Culex_, L., whether known by the name of gnats or mosquitos[168]. Pliny, after Aristotle, distinguishes well between _Hymenoptera_ and _Diptera_, when he says the former have their sting in their tail, and the latter in their mouth; and that to the one this weapon is given as the instrument of vengeance, and to the other of avidity[169]. But the instrument of avidity in the genus of which I am speaking, is even more terrible than that of vengeance in most insects that are armed with it: like the latter also, as appears from the consequent inflammation and tumour, it instills into its wound a poison; the principal use of which, however, is to render the blood more fluid and fitter for suction. This weapon, which is more complex than the sting of hymenopterous insects, consisting of five pieces besides the exterior sheath, some of which seem simply lancets, while others are barbed like the spicula of a bee's sting, is at once calculated for piercing the flesh and forming a siphon adapted to imbibe the blood[170]. There are several species of this genus whose bite is severe, but none is to be compared to the common gnat (_Culex pipiens_, L.), if, as has been generally affirmed, it be synonymous with the mosquito (though perhaps several species are confounded under both names); and to this, the most insatiable of blood-suckers, I shall principally direct your attention[171].

In this country they are justly regarded as no trifling evil; for they follow us to all our haunts, intrude into our most secret retirements, assail us in the city and in the country, in our houses and in our fields, in the sun and in the shade: nay, they pursue us to our pillows, and either keep us awake by the ceaseless hum of their droning pipe, and their incessant endeavours to fix themselves upon our face, or some uncovered part of our body; or, if in spite of them we fall asleep, awaken us by the acute pain which attends the insertion of their oral stings; attacking with most avidity the softer sex, and trying their temper by disfiguring their beauty. But although with us they are usually rather teasing than injurious; yet upon some occasions they have approached nearer to the character of a plague, and emulated with success the mosquitos of other climates. Thus, we are told that in the year 1736 they were so numerous, that vast columns of them were seen to rise in the air from Salisbury cathedral, which at a distance resembled columns of smoke, and occasioned many people to think that the cathedral was on fire. A similar occurrence, in like manner giving rise to an alarm of the church being on fire, took place in July 1812 at Sagan in Silesia[172]. In the following year at Norwich, in May, at about six o'clock in the evening, the inhabitants of that city were alarmed by the appearance of smoke issuing from the upper window of the spire of the cathedral, for which at the time no satisfactory account could be given, but which was most probably produced by the same cause. And in the year 1766, in the month of August, they appeared in such incredible numbers at Oxford as to resemble a black cloud, darkening the air and almost totally intercepting the beams of the sun. One day, a little before sun-set, six columns of them were observed to ascend from the boughs of an apple-tree, some in a perpendicular and others in an oblique direction, to the height of fifty or sixty feet. Their bite was so envenomed, that it was attended by violent and alarming inflammation; and one when killed usually contained as much blood as would cover three or four square inches of wall[173]. Our great poet Spenser seems to have witnessed a similar appearance of them, which furnished him with the following beautiful simile:

As when a swarme of gnats at eventide Out of the fennes of Allan doe arise, Their murmuring small trumpets sownden wide, Whiles in the air their clust'ring army flies, That as a cloud doth seem to dim the skies; Ne man nor beast may rest or take repast For their sharp wounds and noyous injuries. Till the fierce northern wind with blust'ring blast Doth blow them quite away, and in the ocean cast.

In Marshland in Norfolk, as I learn from a lady who had an opportunity of personal inspection, the inhabitants are so annoyed by the gnats, that the better sort of them, as in many hot climates, have recourse to a gauze covering for their beds, to keep them off during the night. Whether this practice obtains in other fen districts I do not know.

But these evils are of small account compared with what other countries, especially when we approach the poles or the line, are destined to suffer from them; for there they interfere so much with ease and comfort, as to become one of the worst of pests and a real misery of human life. We may be disposed to smile perhaps at the story Mr. Weld relates from General Washington, that in one place the mosquitos were so powerful as to pierce through his boots[174] (probably they crept within the boots): but in various regions scarcely any thing less impenetrable than leather can withstand their insinuating weapons and unwearied attacks. One would at first imagine that regions where the polar winter extends its icy reign would not be much annoyed by insects: but however probable the supposition, it is the reverse of fact, for nowhere are gnats more numerous. These animals, as well as numbers of the _Tipulariæ_ of Latreille, seem endowed with the privilege of resisting any degree of cold, and of bearing any degree of heat. In Lapland their numbers are so prodigious as to be compared to a flight of snow when the flakes fall thickest, or to the dust of the earth. The natives cannot take a mouthful of food, or lie down to sleep in their cabins, unless they be fumigated almost to suffocation. In the air you cannot draw your breath without having your mouth and nostrils filled with them; and unguents of tar, fish-grease, or cream; or nets steeped in fetid birch-oil, are scarcely sufficient to protect even the case-hardened cuticle of the Laplander from their bite[175]. In certain districts of France, the accurate Reaumur informs us that he has seen people whose arms and legs have become quite monstrous from wounds inflicted by gnats; and in some cases in such a state as to render it doubtful whether amputation would not be necessary[176]. In the neighbourhood of the Crimea the Russian soldiers are obliged to sleep in sacks to defend themselves from the mosquitos; and even this is not a sufficient security, for several of them die in consequence of mortification produced by the bites of these furious blood-suckers. This fact is related by Dr. Clarke, and to its probability his own painful experience enabled him to speak. He informs us that the bodies of himself and his companions, in spite of gloves, clothes, and handkerchiefs, were rendered one entire wound, and the consequent excessive irritation and swelling excited a considerable degree of fever. In a most sultry night, when not a breath of air was stirring, exhausted by fatigue, pain, and heat, he sought shelter in his carriage: and, though almost suffocated, could not venture to open a window for fear of the mosquitos. Swarms nevertheless found their way into his hiding-place; and, in spite of the handkerchiefs with which he had bound up his head, filled his mouth, nostrils, and ears. In the midst of his torment he succeeded in lighting a lamp, which was extinguished in a moment by such a prodigious number of these insects, that their carcases actually filled the glass chimney, and formed a large conical heap over the burner. The noise they make in flying cannot be conceived by persons who have only heard gnats in England. It is to all that hear it a most fearful sound[177]. Travellers and mariners who have visited warmer climates give a similar account of the torments there inflicted by these little demons. One traveller in Africa complains that after a fifty miles journey they would not suffer him to rest, and that his face and hands appeared, from their bites, as if he was infected with the small-pox in its worst stage[178]. In the East, at Batavia, Dr. Arnold, a most attentive and accurate observer, relates that their bite is the most venomous he ever felt, occasioning a most intolerable itching, which lasts several days. The sight or sound of a single one either prevented him from going to bed for a whole night, or obliged him to rise many times. This species, which I have examined, is distinct from the common gnat, and appears to be nondescript. It approaches nearest to _C. annulatus_, but the wings are black and not spotted. And Captain Stedman in America, as a proof of the dreadful state to which he and his soldiers were reduced by them, mentions that they were forced to sleep with their heads thrust into holes made in the earth with their bayonets, and their necks wrapped round with their hammocks[179].

From Humboldt also we learn that "between the little harbour of Higuerote and the mouth of the Rio Unare the wretched inhabitants are accustomed to stretch themselves on the ground, and pass the night buried in the sand three or four inches deep, leaving out the head only, which they cover with a handkerchief." This illustrious traveller has given an account in detail of these insect plagues, by which it appears that amongst them there are diurnal, crepuscular, and nocturnal species, or genera: the _Mosquitos_ or _Simulia_ flying in the day; the _Temporaneros_, probably a kind of _Culex_, flying during twilight; and the _Zancudos_ or _Culices_ in the night. So that there is no rest for the inhabitants from their torment day or night, except for a short interval between the retreat of one species and the attack of another. We learn from this author that the sting or bite of the _Simulium_ is as bad as that of the _Stomoxys_ before noticed[180].

It is not therefore incredible that Sapor, king of Persia, as is related, should have been compelled to raise the siege of Nisibis by a plague of gnats, which attacking his elephants and beasts of burthen, so caused the rout of his army, whatever we may think of the miracle to which it was attributed[181]; nor that the inhabitants of various cities, as Mouffet has collected from different authors[182], should, by an extraordinary multiplication of this plague, have been compelled to desert them; or that by their power to do mischief, like other conquerors who have been the torment of the human race, they should have attained to fame, and have given their name to bays, towns, and even to considerable territories[183].

And now, which seems to you the greater terror, that the forest should resound with the roar of the lion or the tiger, or with the hum of the gnat? Which evil is most to be deprecated, the neighbourhood of these ferocious animals, terrible as they are for their cruelty and strength, or to live amidst the polar or tropical myriads of mosquitos, and be subject to the torture of their incessant attacks? When you consider that from the one, prudence and courage may secure or defend us without any material sacrifice of our daily comforts; while to be at rest from the other, we must either render ourselves disgusting by filthy unguents, or be suffocated by fumigations, or be content to be bound, head, hand and foot, shut out from the respiration of the common air, and even thus scarcely escape from their annoyance; you will feel convinced that the former is the more tolerable evil of the two, and be inclined to think that those cities, from which the lions were driven away by the more powerful gnats, were no great gainers by the exchange[184]. With what grateful hearts ought the privileged inhabitants of these happy islands to acknowledge and glorify the goodness of that kind Providence which has distinguished us from the less favoured nations of the globe, by what may be deemed an immunity from this tormenting pest! for the inroads which they make on our comfort, when contrasted with what so many other people of every climate suffer from them, are mere nothings. When we behold on one side of us the ravages of the wide-wasting sword, on another those of infectious disease or pestilence, on a third famine destroying its myriads, and on a fourth life rendered uncomfortable by the terror of "noisome beasts," and the attack of noxious insects: and when we look at home and see every one eating his bread in peace, protected in his enjoyments by equal laws executed by a mild government under a paternal king, without fearing the sword of the oppressor; not scourged by pestilence or famine, exposed to the attack of no ferocious animal, and comparatively speaking but slightly visited by the annoyance of insect tormentors; and especially when we further reflect that it is his mercy and not our merits which has induced him thus to overwhelm us with blessings, while other countries have been made to drink deep of the cup of his fury, we shall see reason for an increased degree of thankfulness and gratitude, and, instead of repining, be well content with our lot, though our offences have not wholly been passed over, and we have been "beaten with few stripes."

* * * * *

Besides the insects that seek to make us their food, there are others, which, although we are apt to regard them with the greatest horror, do not attack us with this view, but usually to revenge some injury which they have received, or apprehend from us. Foremost in the list of these are those with four wings, which, according to the observation of Pliny before quoted, carry their weapon, an instrument of revenge, in their _tail_. These all belong to the Linnean order _Hymenoptera_; and the tremendous arms with which they annoy us, are two darts finer than a hair, furnished on their outer side at the end with several barbs not visible to the naked eye, and each moving in the groove of a strong and often curved sheath, frequently mistaken for the sting, which, when the darts enter the flesh, usually injects a drop of subtle venom, furnished from a peculiar vessel in which it is secreted, into the wound, occasioning, especially if the darts be not extracted, a considerable tumour, accompanied by very acute pain. Many insects are thus armed and have this power. Twice I have been stung by an Ichneumon; first by one with a concealed sting, and afterwards by another of the family of _Pimpla Manifestator_, with a very long exerted one. I had held the insect by its sting, which it withdrew from between my fingers with surprising force, and then, as if in revenge, stung me. _Pompilus viaticus_, one of the spider-wasps, once, in this way, gave me acute pain. Mr. W. S. MacLeay states that at the Havana he was once stung by a gigantic _Pompilus_ (probably _P. Heros_), from which he suffered a very short-lived pain, but the wound bled as if punctured by a pin. The bleeding he conjectures carried off the venom. But the insects which in this respect principally attract our notice by exciting our fears, are the hive-bee, the wasp, and the hornet. The first of these, the _bee_, sometimes manifests an antipathy to particular individuals, whom it attacks and wounds without provocation; but the two last, though apparently the most formidable, are not so ill-tempered as they are conceived to be, seldom molesting those who do not first interfere with or disturb them. We learn from Scripture that the _hornet_ (but whether it was the common species is uncertain) was employed by Providence to drive out the impious inhabitants of Canaan, or subdue them under the hand of the Israelites[185].--The effect produced by the sting of these animals is different in different persons. To some they occasion only a very slight inconvenience or a momentary pain; others feel the smart of the wounds which they inflict for several days, and are thrown into fevers by them; and to some they have even proved fatal[186]. Yet these insects are certainly, in general, but a trifling evil. They become, however, especially _wasps_, a very serious one to many, from the mere dread of being stung by them, even though they should not carry their fears to the same length with the lady mentioned by Dr. Fairfax[187], in the _Philosophical Transactions_, who had such a horror of them, that during the season in which they abound in houses, she always confined herself to her apartment.

_Ants_ are insects of this order, which, though our indigenous species may be regarded as harmless, in some countries are gifted with double means of annoyance, both from their sting and their bite. A green kind in New South Wales was observed by Sir Joseph Banks to inflict a wound scarcely less painful than the sting of a bee[188]. Another, from the intolerable anguish occasioned by its bite, which resembles that produced by a spark of fire, and seems attended by venom, is called the fire-ant. Captain Stedman relates that this caused a whole company of soldiers to start and jump about as if scalded with boiling water; and its nests were so numerous that it was not easy to avoid them[189]. We are told of a third species, which emulates the scorpion in the malignity of its sting or bite[190]. Knox, in his account of Ceylon, mentions a black ant, called by the natives _Coddia_, which he says "bites desperately, as bad as if a man were burnt by a coal of fire; but they are of a noble nature, and will not begin unless you disturb them." The reason the Cinghalese assign for the horrible pain occasioned by their bite is curious, and will serve to amuse you. "Formerly these ants went to ask a wife of the _Noya_, a venomous and noble kind of snake; and because they had such a high spirit to dare to offer to be related to such a generous creature, they had this virtue bestowed upon them, that they should sting after this manner. And if they had obtained a wife of the Noya, they should have had the privilege to sting full as bad as he[191]." Stedman's story of a large ant that stripped the trees of their leaves, to feed, as was supposed, a blind serpent under ground[192], is somewhat akin to this: as is also another, related to me by a friend of mine, of a species of Mantis, now in my cabinet, taken in one of the Indian islands, which, according to the received opinion amongst the natives, was the parent of all their serpents. Whence, unless perhaps from their noxious qualities, could this idea of a connexion between insects and these reptiles be derived? But to return from this digression----Madame Merian's Ant of Visitation (_Œcodoma cephalotes_) will be considered in a subsequent letter: but I cannot here omit a circumstance mentioned by Don Felix de Azara, a late Spanish traveller, who confirms her account,--that these animals are so alarming and tremendous in their attacks, that if they enter a house in the night, the inhabitants are obliged to rise with all speed and run off in their shirts.

I must next direct your attention to an insect, which perhaps more than any other has in every age been an object of terror and abhorrence--I mean the redoubted _scorpion_. And though I shall not, with Aristotle, tell you of Persian kings employing armies for several days in destroying them; or, with Pliny, of countries that they have depopulated; yet my account will not be devoid of that species of interest which the dread of its power to do us injury imparts to any object. Could you see one of these ferocious animals, perhaps a foot in length, a size to which they sometimes attain, advancing towards you in their usual menacing attitude, with its claws expanded, and its many-jointed tail turned over its head; were your heart ever so stout, I think you would start back and feel a horror come across you; and, though you knew not the animal, you would conclude that such an aspect of malignity must be the precursor of malignant effects. Nor would you be mistaken, as you will presently see. This alarming animal, though like hymenopterous insects it is armed with a sting, is in no respect related to that order, and forms the only genus, at present known, of the others that is so armed. Even its sting is totally different from that of bees, wasps, and other Hymenoptera, being more analogous to the venomous tooth of serpents; it wounds us with no barbed darts concealed in a sheath, but only with a simple incurved mucro terminating an ampullaceous joint. Two orifices, or according to some three, are said to instill the poison, which, we are informed, is sometimes as white as milk. This venom in our European species is seldom attended, except to minor animals, by any very serious consequences; yet when it is communicated by the scorpion of warmer climates it produces more baneful effects. The sting of certain kinds common in South America causes fevers, numbness in various parts of the body, tumours in the tongue, and dimness of sight, which symptoms last from twenty-four to forty-eight hours. The only means of saving the lives of our soldiers who were stung by them in Egypt, was amputation. One species is said to occasion madness; and the black scorpion, both of South America and Ceylon, frequently inflicts a mortal wound[193]. No known animal is more cruel and ferocious in its manners; they kill and devour their own young without pity as soon as they are born, and they are equally savage to their fellows when grown up. Terrible however and revolting as these creatures appear, we are gravely told by Naudé, that there is a species of scorpion in Italy which is domesticated, and put between the sheets to cool the beds during the heats of summer[194]!!

I must next say something of insects that annoy us solely by their _jaws_. Of this description is _Galeodes araneoides_ which is related to the scorpion, although devoid of a sting. The bite of this animal, which is a native of the Cape of Good Hope and of Russia[195], is represented to be often fatal both to man and beast. Another species of _Galeodes_ is described by Professor Lichtenstein, which, from the trivial name that he has given it (_fatalis_), may be supposed to be as venomous as the former[196].

The bite of one of the centipedes (_Scolopendra morsitans_)--the under-jaws, or rather arms, of which are armed with a strong claw, furnished like the sting of the scorpion with an orifice, visible under a common lens[197], from which poison issues--is less tremendous than that of the animal last mentioned: but though not mortal, its wounds are more painful than those produced by the sting of the scorpion; and as these animals creep every where, even into beds, they must be very annoying in warm climates where they abound. Dr. Martin Lister, in his _Travels_, has given us a figure of an insect related to this genus, that he saw in Plumier's collection, which appears to have been eighteen inches in length, and three quarters of an inch in width, having ninety-five legs on each side, the first eight of which are armed with double claws, and two inches of the tail being without legs. It may form a distinct genus, and is probably a native of South America. Yet even this monstrous insect is nothing to those at Carthagena, mentioned by Ulloa, (if indeed we may credit his account, or if his translator has not mistaken his meaning,) which sometimes exceeded a yard in length and five inches in breadth! The bite of this gigantic serpent-like creature, he tells us, is mortal, as well it may, if a timely remedy be not applied. From its cylindrical form it should be a Julus[198].

In this catalogue of noxious insects I must not omit those which every where force themselves upon our notice, and are viewed with general disgust. I mean the numerous family of Arachne, the insidious spiders. Few of these, however, are really personal assailants of man. The principal is that which has given rise to so much discussion, and has so much employed the pens of naturalists and physicians--the famous _Tarentula_ (_Lycosa Tarentula_). The effects ascribed to its wounds, and their wonderful cure supposed to be wrought by music and dancing, have long been celebrated: but after all there seems to have been more of fraud than of truth in the business; and the whole evil appears to consist in swelling and inflammation. Dr. Clavitio submitted to be bitten by this animal, and no bad effects ensued; and the Count de Borch, a Polish nobleman, bribed a man to undergo the same experiment, in whom the only result was a swelling in the hand, attended by intolerable itching. The fellow's sole remedy was a bottle of wine, which charmed away all his pain without the aid of pipe and tabor[199].

There is however a spider (_Theridium_ 13_-guttatum_) the bite of which is said to be very dangerous, and even mortal. Thiébaut de Berneaud, in his _Voyage to Elba_[200], affirms that in the Volterrano he knew that several country people and domestic animals died in consequence of it. And according to Mr. Jackson, a spider, called there the _Tendaraman_, is found in Marocco which has venomous powers equally formidable. The bite of this insect, which is about the size and colour of a hornet but rounder, and spins a web so fine as to be almost invisible, is said to be so poisonous that the person bitten survives but a few hours. In the cork forests the sportsman, eager in his pursuit of game, frequently carries away on his garments this fatal insect, which is asserted always to make towards the head before inflicting its deadly wound[201].

* * * * *

I suspect you will think this list long enough; and I believe it includes the most remarkable insects that assail the surface of our bodies, to answer either the demands of hunger or the stimulus of revenge. There is however a third class of insect annoyers, as I observed at the beginning of this letter, which, though they neither make us their food, nor attack us under the impulse of fear or revenge, incommode us extremely in other ways. These must now be detailed to you.

How extremely unpleasant is the sensation which that very minute fly, _Thrips physapus_, excites in sultry weather, merely by creeping over our skin! I have sometimes found this almost intolerable. A similar torment reckoned by Ulloa a kind of Mosquito, infests the inhabitants of Carthagena in South America. They are there called _Mantas blancas_, and creeping between the threads of the gauze curtains that keep off the former pest, though they do not bite, occasion an itching that is dreadfully tormenting[202]. But these are nothing compared with the teasing attacks of another gnat (_Simulium reptans_), which, as Linné informs us, who misnamed it a Culex, is so incredibly numerous in Lapland, as entirely to cover a man's body, turning a white dress into a black one, occupying the whole atmosphere, filling the mouth, nostrils, eyes, and ears of travellers, and thus preventing respiration, and almost choking them. These little animals, he says, do not bite, but torture incessantly by their titillation[203].--In New South Wales a small ant was observed by Sir Joseph Banks, inhabiting the roots of a plant, which when disturbed rushed out by myriads, and running over the uncovered parts of the body produced a sensation of this kind that was worse than pain.

The common house-fly is with us often sufficiently annoying at the close of summer; but we know nothing of it as a tormentor compared with the inhabitants of southern Europe.--"I met (says Arthur Young in his interesting _Travels through France_) between Pradelles and Thuytz, mulberries and flies at the same time; by the term _flies_ I mean those myriads of them which form the most disagreeable circumstance of the southern climates. They are the first torments in Spain, Italy, and the Olive district of France: it is not that they bite, sting, or hurt, but they buzz, tease, and worry: your mouth, eyes, ears, and nose, are full of them: they swarm on every eatable,--fruit, sugar, milk, every thing is attacked by them in such myriads, that if they are not incessantly driven away by a person who has nothing else to do, to eat a meal is impossible. They are however caught on prepared paper and other contrivances with so much ease and in such quantities, that were it not from negligence, they could not abound in such incredible quantities. If I farmed in these countries, I think I should manure four or five acres every year with dead flies.--I have been much surprised that the late learned Mr. Harmer should think it odd to find, by writers who treated of southern climates, that driving away flies was an object of importance. Had he been with me in Spain and in Languedoc in July and August, he would have been very far from thinking there was any thing odd in it[204]."

Our friend Captain Green, of the sixth regiment of the East India Company's native troops, relates to me, that in India, when the mangoes are ripe, which is the hottest part of the summer, a very minute black fly makes its appearance, which, because it flies in swarms into the eyes, is very troublesome, and causes much pain, is called there the _eye-fly_. At this season the eyes are attacked by a disease, supposed to be occasioned by eating the mangoes, but more probably the result of the irritation produced by the fly in question, which, however, they admit, carries the infection from one person to another.

You know that the hairs taken from the pods of _Dolichos pruriens_ and _urens_, L., commonly called _Cowhage_ and _Cow-itch_[205], occasion a most violent itching, but perhaps are not aware that those of the _caterpillars_ of several Moths will produce the same disagreeable effect. One of these is the procession moth, (_Lasiocampa processionea_) of which Reaumur has given so interesting an account. In consequence of their short stiff hairs sticking in his skin, after handling them, he suffered extremely for several days; and being ignorant at first of the cause of the itching, and rubbing his eyes with his hands, he brought on a swelling of the eye-lids, so that he could scarcely open them. Ladies were affected even by going too near the nest of the animal, and found their necks full of troublesome tumours, occasioned by short hairs, or fragments of hair, brought by the wind[206]. Of this nature also is the famous Pityocampa of the ancients, the moth of the fir (_Lasiocampa Pityocampa_), the hairs of which are said to occasion a very intense degree of pain, heat, fever, itching and restlessness. It was accounted by the Romans a very deleterious poison, as is evident from the circumstance of the Cornelian law "_De sicariis_" being extended to persons who administered _Pityocampa_[207].

In these cases the injury is the consequence of irritation produced by the hair of the animal; but there are facts on record, which prove that the juices of many insects are equally deleterious. Amoreux, from a work of Turner, an English writer on cutaneous diseases, has given the following remarkable history of the ill effects produced by those of _spiders_. When Turner was a young practitioner, he was called to visit a woman, whose custom it was, every time she went into the cellar with a candle, to burn the spiders and their webs. She had often observed, when she thus cruelly amused herself, that the odour of the burning spiders had so much affected her head, that all objects seemed to turn round, which was occasionally succeeded by faintings, cold sweats, and slight vomitings: but, notwithstanding this, she found so much pleasure in tormenting these poor animals, that nothing could cure her of this madness, till she met with the following accident: The legs of one of these unhappy spiders happened to stick in the candle, so that it could not disengage itself; and, the body at length bursting, the venom was ejaculated into the eyes and upon the lips of its persecutrix. In consequence of this, one of the former became inflamed, the latter swelled excessively, even the tongue and gums were slightly affected, and a continual vomiting attended these symptoms. In spite of every remedy the swelling of the lips continued to increase, till at length an old woman, by the simple application for fifteen days of the leaves and juice of plantain, together with some spider's web, ran away with all the glory of the cure[208]. Ulloa gives us a remarkable account of a species of spider, or perhaps mite, of a fiery red colour, common in Popayan, called _Coya_ or _Coyba_, and usually found in the corners of walls and among the herbage, the venom of which is of such malignity, that on crushing the insect, if any fall on the skin of either man or beast, it immediately penetrates into the flesh, and causes large tumours, which are soon succeeded by death. Yet, he further observes, if it be crushed between the palms of the hands, which are usually callous, no bad consequence ensues. People who travel along the valleys of the Neyba, where these insects abound, are warned by their Indian attendants, if they feel any thing stinging them, or crawling on their neck or face, not so much as to lift up their hand to the place, the texture of the Coya being so delicate that the least force causes them to burst, without which there is no danger, as they seem otherwise harmless animals. The traveller points out the spot where he feels the creature to one of his companions, who, if it be a Coya, blows it away. If this account does not exaggerate the deleterious quality of the juices of this insect, it is the most venomous animal that is known; for he describes it as much smaller than a bug. The only remedy to which the natives have recourse for preventing the ill effects arising from its venom is, on the first appearance of the swelling, to swing the patient over the flame of straw or long grass, which they do with great dexterity: after this operation he is reckoned to be out of danger[209].--The poisoned arrows which Indians employ against their enemies have been long celebrated. The Coya may, in the western world, have furnished the poison for this purpose. An author quoted in Lesser tells us that an ant as big as a bee is sometimes used, and that the wound inflicted by weapons tinctured with their venom is incurable. Patterson also gives a recipe by which the natives of the southern extremity of Africa prepare what they reckon the most effectual poison for the point of their arrows. They mix the juice of a species of Euphorbia, and a caterpillar that feeds on a kind of sumach (_Rhus_, L.), and when the mixture is dried it is fit for use[210].

And now I think you will allow that I have made out a tolerable list of insects that attack or annoy man's body externally, and a sufficiently doleful history of them. That the subject, however, may be complete, I shall next enumerate those that, not content with afflicting him with _exterior_ pain or evil, whether on the surface or under the skin, bore into his flesh, descend even into his stomach and viscera; derange his whole system, and thus often occasion his death. The punitive insects here employed are usually larvæ of the various orders, and they are the cause of that genus of diseases I before noticed, and proposed to call _Scolechiasis_.

I shall begin my account with the first order of Linné, because people in general seem not aware that any _beetles_ make their way into the human _stomach_. Yet there is abundant evidence, which proves beyond controversy that the meal-worm (_Tenebrio Molitor_), although its usual food is flour, has often been voided both by male and female patients; and in one instance is stated to have occasioned death[211]. How these grubs should get into the stomach it is difficult to say--perhaps the eggs may have been swallowed in some preparation of flour. But that the animal should be able to sustain the heat of this organ, so far exceeding the temperature to which it is usually accustomed, is the most extraordinary circumstance of all.--Dr. Martin Lister, who to the skill of the physician added the most profound knowledge of nature, mentions an instance, communicated to him by Mr. Jessop, of a girl who voided three hexapod larvæ similar to what are found in the carcases of birds[212], probably belonging either to the genus _Dermestes_, or _Anthrenus_: and in the _German Ephemerides_ the case also of a girl is recorded, from an abscess in the _calf_ of whose _leg_ crept black worms resembling beetles[213].

The larvæ of some beetle, as appears from the description, seem to have been ejected even from the _lungs_. Four of these, of which the largest was nearly three quarters of an inch long, were discovered in the mucus expelled after a severe fit of coughing by a lady afflicted with a pulmonary disease; and similar larvæ of a smaller size were once afterwards discharged in the same way[214].

No one would suppose that _caterpillars_, which feed upon vegetable substances, could be met with alive in the stomach; yet Dr. Lister gives an account of a boy who vomited up several, which, he observes, had sixteen legs[215]. The eggs perhaps might have been swallowed in salad; and, as vegetables make a part of most people's daily diet, enough might have passed into the stomach to support them when hatched.--Linné tells us that the caterpillar of a moth (_Aglossa pinguinalis_), common in houses, has also been found in a similar situation, and is one of the worst of our insect infesters.--In a very old tract, which gives a figure of the insect, a caterpillar of the almost incredible length of the middle finger is said to have been voided from the _nostrils_ of a young man long afflicted with dreadful pains in his head[216].--But the most extraordinary account with respect to lepidopterous larvæ (unless he has mistaken his insects) is given by Azara, the Spanish traveller before quoted; who says that in South America there is a large brown _moth_, which deposits its young in a kind of saliva upon the flesh of persons who sleep naked; these introduce themselves under the skin without being perceived, where they occasion swelling attended by inflammation and violent pain. When the natives discover it, they squeeze out the larvæ, which usually amount to five or six[217].

But amongst all the orders, none is more fruitful in devourers of man than the _Diptera_. The Gad-fly (_Œstrus_, L.) you have, doubtless, often heard of, and how sorely it annoys our cattle and other quadrupeds; but I suspect have no notion that there is a species appropriated to man. The existence, indeed, of this species seems to have been overlooked by entomologists (though it stands in Gmelin's edition of the _Systema Naturæ_[218], upon the authority of the younger Linné,) till Humboldt and Bonpland mentioned it again. Speaking of the low regions of the torrid zone, where the air is filled with those myriads of mosquitos which render uninhabitable a great and beautiful portion of the globe, they observe that to these may be joined the _Œstrus Hominis_, which deposits its eggs in the skin of man, causing there painful tumours[219]. Gmelin says that it remains beneath the skin of the abdomen six months, penetrating deeper, if it be disturbed, and becoming so dangerous as sometimes to occasion death. The imago he describes as being of a brown colour, and about the size of the common house-fly; so that it is a small species compared with the rest of the genus. Even the gad-fly of the ox, leaving its proper food, has been known to oviposit in the jaw of a woman, and the bots produced from the eggs finally caused her death[220].--Other flies also of various kinds thus penetrate into us, either preying upon our flesh, or getting into our intestines. Leeuwenhoek mentions the case of a woman whose leg had been enlarging with glandular bodies for some years. Her surgeon gave him one that he had cut from it, in which were many small maggots: these he fed with flesh till they assumed the pupa, when they produced a fly as large as the flesh-fly[221].--A patient of Dr. Reeve of Norwich, after suffering for some time great pain, was at last relieved by voiding a considerable number of maggots, which agree precisely with those described by De Geer as the larvæ of his _Musca domestica minor_, (_Anthomyia canicularis_, Meig.) a fly which he speaks of as very common in apartments[222].--In Paraguay the flesh-flies are said to be uncommonly numerous and noxious. Azara relates[223] that, after a storm, when the heat was excessive, he was assailed by such an army of them, that in less than half an hour his clothes were quite white with their eggs, so that he was forced to scrape them off with a knife; adding, that he has known instances of persons, who, after having bled at the nose in their sleep, were attacked by the most violent headaches; when at length several great maggots, the offspring of these flies, issuing from their nostrils, gave them relief.--In Jamaica a large blue fly buzzes about the sick in the last stages of fever; and when they sleep or doze with their mouths open, the nurses find it very difficult to prevent these flies from laying their eggs in the nose, mouth, or gums. An instance is recorded of a lady who, after recovering from a fever, fell a victim to the maggots of this fly, which from the nose found their way through the _os cribriforme_ into the cavity of the skull, and afterwards into the brain[224]. One of the most shocking cases of _Scolechiasis_ I ever met with is related in Bell's _Weekly Messenger_ in the following words: "On Thursday, June 25, died at Asbornby, (_Lincolnshire_) John Page, a pauper belonging to Silk-Willoughby, under circumstances truly singular. He being of a restless disposition, and not choosing to stay in the parish workhouse, was in the habit of strolling about the neighbouring villages, subsisting on the pittance obtained from door to door: the support he usually received from the benevolent was bread and meat; and after satisfying the cravings of nature, it was his custom to deposit the surplus provision, particularly the meat, betwixt his shirt and skin. Having a considerable portion of this provision in store, so deposited, he was taken rather unwell, and laid himself down in a field in the parish of Scredington--when from the heat of the season at that time, the meat speedily became putrid, and was of course struck by the flies: these not only proceeded to devour the inanimate pieces of flesh, but also literally to prey upon the living substance; and when the wretched man was accidentally found by some of the inhabitants, he was so eaten by the maggots that his death seemed inevitable. After clearing away as well as they were able these shocking vermin, those who found Page conveyed him to Asbornby, and a surgeon was immediately procured, who declared that his body was in such a state that dressing it must be little short of instantaneous death; and in fact the man did survive the operation but a few hours. When first found, and again when examined by the surgeon, he presented a sight loathsome in the extreme; white maggots of enormous size were crawling in and upon his body, which they had most shockingly mangled, and the removing of the external ones served only to render the sight more horrid[225]."--A medical friend of mine, at Ipswich, gave me this winter an apode larva voided by a person of that place with his urine, which I now preserve in spirits and can show you when you visit me. It appears to me to belong to the _Diptera_ order, yet not to the fly tribes (_Tanystoma_, Latr.), but rather to the _Tipulariæ_ of that author, with which however it does not seem to agree so entirely as to take away all doubt. It is a very singular larva, and I can find none in any author that I have had an opportunity of consulting which at all resembles it. That you may know it, should you chance to meet with it, I shall here describe it. _Body_, three fourths of an inch in length, and about a line in breadth; opaque, of a pale yellow colour; cylindrical, tapering somewhat at each extremity; consisting of twenty articulations without the head: _Head_ reddish brown, heartshaped, much smaller than the following joint; armed with two unguiform mandibles; with a biarticulate palpus attached exteriorly to the base of each. These mandibles appear to be moved by a narrow black central tendon under the dorsal skin terminating a little beyond the base of the first segment; besides this, there are four others, two on each side of it, the outer ones diverging, much slenderer, and very short. The last or anal joint of the body very minute; exerting two short, filiform horns, or rather respiratory organs. I could discover, in this animal, no respiratory plates, such as are found in the larvæ of _Muscidæ_, _&c._ nor were the tracheæ visible. When given to me, it was alive and extremely active, writhing itself into various contortions with great agility. It moved, like other dipterous larvæ, by means of its mandibles. Upon wetting my fingers more than once, to take it up when it had fallen from a table upon which it was placed, the saline taste with which it was imbued was so powerful that it was some time before it was dissipated from my mouth.--I shall only mention one more instance, because it is a singular one. The larva of _Helophilus pendulus_, a fly peculiarly formed by nature for inhabiting fluids, has been found in the stomach of a woman[226].

You will smile when I tell you that I have met with the prescription of a famous urine-doctor, in which he recommends to his credulous patient to take a certain number of _sow bugs_ per diem, by this name distinguishing, as I suppose, the pill-millepede (_Armadillo vulgaris_), once a very favourite remedy. What effect they produced in this case I was not informed; but the learned Bonnet relates that he had seen a certificate of an English physician, dated July 1763, stating that, some time before, a young woman who had swallowed these animals alive, as is usually done, threw up a prodigious number of them of all sizes, which must have bred in her stomach[227].--Another apterous species appears to have been detected in a still more remarkable situation. Hermann, the author of the admirable _Mémoire Apterologique_, whose untimely death is so much to be lamented, informs us that an Acarus figured and described in his work (_A. marginatus_), was observed by his artist running on the _corpus callosum_ of the _brain_ of a patient in the military hospital at Strasbourg, which had been opened but a minute before and the two hemispheres and the _pia mater_ just separated. He adds that this is not the first time that insects have been found in the brain. Cornelius Gemma, in his _Cosmocritica_, p. 241, says that on dissecting the brain of a woman there were found in it abundance of vermicles and _punaises_[228].

It was customary in many countries in ancient times to punish certain malefactors by exposing them to be devoured by wild beasts: but to expose them to _insects_ for the same purpose was a refinement in cruelty, which seems to have been peculiar to the despots of Persia. We are informed that the most severe punishment amongst the Persians was that of shutting up the offender between two boats of equal size; they laid him in one of them upon his back, and covered him with the other, his hands, feet, and head being left bare. His face, which was placed full in the sun, they moistened with honey, thus inviting the flies and wasps, which tormented him no less than the swarms of maggots that were bred in his excrements and body, and devoured him to the very entrails. He was compelled to take as much food as was necessary to support life, and thus existed sometimes for several days. Plutarch informs us that Mithridates, whom Artaxerxes Longimanus condemned to this punishment, lived seventeen days in the utmost agony; and that, the uppermost boat being taken off at his death, they found his flesh all consumed, and myriads of worms gnawing his bowels[229]. Could any natural objects be made more horrible and effectual instruments of torture than _insects_ were in this most diabolical invention of tyranny?

In this enumeration of evils derived from insects, I must not wholly pass over the serious and sometimes fatal effects produced upon some persons by eating honey, or even by drinking mead. I once knew a lady upon whom these acted like poison, and have heard of instances in which death was the consequence. Sometimes, when bees extract their honey from poisonous plants, such results have not been confined to individuals of a particular habit or constitution. A remarkable proof of this is given by Dr. Barton in the fifth volume of _The American Philosophical Transactions_. In the autumn and winter of the year 1790, an extensive mortality was produced amongst those who had partaken of the honey collected in the neighbourhood of Philadelphia. The attention of the American Government was excited by the general distress, a minute inquiry into the cause of the mortality ensued, and it was satisfactorily ascertained that the honey had been chiefly extracted from the flowers of _Kalmia latifolia_.

Amongst other _direct_ injuries occasioned by these creatures, perhaps, out of regard for the ladies, I ought to notice the alarm which many of them occasion to the loveliest part of the creation. When some females retire from society to avoid a wasp; others faint at the sight of a spider; and others, again, die with terror if they hear a death-watch: these groundless apprehensions and superstitious alarms are as much real evils to those who feel them, as if they were well founded. But having already adverted to this subject, I shall here only quote the observation of a wise man, that "Fear is a betraying of the succours that reason offereth[230]." The best remedy, therefore, in such cases is going to reason for succour. In a few instances, indeed, the evil may take root in a constitutional defect, for there seems to be some foundation for the doctrine of natural antipathies: but, generally speaking, in consequence of the increased attention to Natural History, the reign of imaginary evils is ceasing amongst us, and what used to shake the stout hearts of our superstitious ancestors with anile terrors, is become a subject of interesting inquiry to their better informed descendants, even of the weaker sex.

And now, my friend, I flatter myself you feel disposed to own the truth of my position, however it might startle you at first, and will candidly acknowledge that I have proved the empire of these despised insects over man's person: and that, instead of being a race of insignificant creatures, which we may safely overlook, as having no concern with, they may, in the hands of Divine Providence, and even of man, become to us fearful instruments of evil and of punishment. I shall next endeavour to give you some idea of the _indirect_ injuries which they occasion us by attacking our property, or interfering with our pleasure or comfort--but this must be the subject of another letter.

I am, &c.

FOOTNOTES:

[106] Joel ii. 25.

[107] _On the Blight in Corn_, p. 9.

[108] Leeuw. _Epist._ 98. 1696.

[109] Bingley, _Anim. Biogr._ first edition, iii. 437. St. Pierre's _Studies_, &c. i. 312.

[110] _Hist. Animal._ l. 5. c. 31.

[111] From the terms employed by Aristotle and Dr. Mead in their Account of these cases, it appears that the animal they meant could not be maggots, but something bearing a more general resemblance to lice.

[112] _On Cutaneous Diseases_, 87, 88; and _t._ 7. _f._ 4.

[113] Latreille at first considered this as belonging to a distinct genus from the common mite (_Acarus domesticus_), which he named _Sarcoptes_; but upon its being discovered that it also has mandibles, he has suppressed it. _N. Dict. d'Hist. Nat._ xxi. 221.

[114] _On Morbid Poisons_, 306, 307.

[115] Mouffet, 267.

[116] _Medica Sacra_, 104, 105.

[117] It is to be hoped this new word may be admitted, as the _laying of eggs_ cannot otherwise be expressed without a periphrasis. For the same reason its substantive _Oviposition_ will be employed.

[118] _Mém. Apterologique_, 19.

[119] Insecta ejusmodi minutissima, forte _Acaros_ diversæ speciei causas esse diversorum morborum contagiosorum, ab analogia et experientia hactenus acquisita, facili credimus negotio. _Amœn. Ac._ v. 94.

[120] _Amœn. Ae._ v. 94-98.

[121] Mouffet, 266.

[122] Acarus sub ipsa pustula minimè quærendus est, sed longius recessit, sequendo rugam cuticulæ observatur. _Amœn. Ac._ v. 95. not. **.

[123] _Observations_, &c. 296.

[124] Extractus acu et super ungue positus, movet se si solis etiam calore adjuvetur. _ubi supr._ Ungui impositus vix movetur: si vero oris calido halitu affletur, agilis in ungue cursitat. _Fn. Suec._ 1975.

[125] Neque Syrones isti sunt de pediculorum genere, ut Johannes Langius ex Aristotele videtur asserere: nam illi extra cutem vivunt, hi vero non. _ubi supr._

[126] Imo ipsi _Acari_ præ exiguitate indivisibiles, ex cuniculis prope aquæ lacum quos foderunt in cute, acu extracti et ungue impositi, caput rubrum, et pedes quibus gradiuntur ad solem produnt. p. vi.

[127] Teredo sive exiguus vermiculus, qui subter cutim erodit agitque cuniculos in pruriginosis manibus. Gouldman tells us these _Acari_ were also called _Hand-worms_. Another English name is given in Mouffet, viz. _Wheale-worms_.

[128] _Osservazioni intorno à pellicelli del corpo umano fatte dal Dottor_ Gio Cosimo Bonomo, &c. _f._ 1-3. Baker _On Microsc._ i. _t._ 13. _f._ 2.

[129] De Geer, vii. _t._ 5. _f._ 12. 14.

[130] _Mém. Apterologique_, 79.

[131] I am informed by my learned friend Alexander MacLeay, Esq. late Secretary to the Linnean Society, that, in the north of Scotland, the insect of the itch is well known, and easily discovered and extracted.

[132] This opinion Dr. Bateman thinks probably the true one. _Cutan. Dis._ 197.

[133] It may be mentioned here as a remarkable fact, that the _Acarus Scabiei_ was discovered by M. Latreille upon a New Holland quadruped (_Phascolomys fusca_, Geoffr.) of the Marsupian tribe. _N. Dict. d'Hist. Nat._ xxi. 222.

[134] _Amœn. Ac._ ubi supr. 101.

[135] _Traités de Chirurgie_, &c. Leipsig. 1792.

[136] _Mém. Apterolog._ 78.

[137] _In Artaxerx._

[138] _Il._ χ. l. 599. ω l. 414.

[139] Τα δε εντομα παντα σκωληκοτοκει. _De Generat. Animal._ l. 2. c. 1.

[140] _Il._ υ. l. 654-5.

[141] Γης εντερα. _De Animal. Incessu_, c. 9. _De Generat. Animal._ l. 3. c. 11.

[142] Mark ix. 44. 46. 48.

[143] Σκωληκοβρωτος. Acts xii. 23.

[144] Linn. _Lach. Lapp._ ii. 32. note *.

[145] Latreille after De Geer (vii. 153--.) supposes the _Pique_ and _Nigua_ of Ulloa to be synonymous with _Ixodes americanus_, L. _Hist. Nat._ vii. 364. but it is evident from _Ulloa's_ description (_Voy._ i. 63. Engl. Trans.) that they are synonymous with the _Chigoe_, or _Pulex penetrans_.

[146] See above p. 50.

[147] Captain Hancock, late commander of His Majesty's ship the Foudroyant, to whose friendly exertions I am indebted for one of the finest collections of Brazil insects ever brought to England, informs me that they will attack any exposed part of the body. He had them once in his hand.

[148] Piso and Margr. _Ind._ 289.

[149] p. 65.

[150] _Personal Narrative_, E. T. v. 101.

[151] _Natural. Miscell._, ii. t. 42.

[152] Lindley in the _Royal Military Chronicle_ for March 1815, p. 459.

[153] I owe this information to the late Robinson Kittoe, Esq. formerly clerk of the Cheque in the King's Yard, Woolwich.

[154] Lesser _L._ ii. 222, note *.

[155] De Geer, vii. 154-60.

[156] _Theatr. Ins._ 270. This happened in 1503; which circumstance refutes Southall's opinion that bugs were not known in England before 1670.

[157] Rai. _Hist. Ins._ 7. Mouffet. 269. They were called also _punez_, from the French _punaise_.

[158] Hence our English word _Bug-bear_. In Matthews's _Bible_, Ps. xci. 5. is rendered, "Thou shalt not nede to be afraid of any _bugs_ by night." The word in this sense often occurs in Shakespear. _Winter's Tale_, act iii. sc. 2. 3. _Hen._ VI. act v. sc. 2. _Hamlet_, act v. sc. 2. See Douce's _Illustrations of Shakespear_, i. 329.

[159] The Banian hospital at Surat is a most remarkable institution. At my visit, the hospital contained horses, mules, oxen, sheep, goats, monkeys, poultry, pigeons, and a variety of birds. The most extraordinary ward was that appropriated to rats and mice, _bugs_, and other noxious vermin. The overseers of the hospital frequently hire beggars from the streets, for a stipulated sum, to pass a night amongst the _fleas_, _lice_, and _bugs_, on the express condition of suffering them to enjoy their feast without molestation. Forbes's _Oriental Memoirs_.

[160] Nicholson's _Journal_, xvii. 40.

[161] Proboscis in cutem intrusa acerrimum dolorem excitat, qui tamen brevi cessat. Rai. _Hist. Ins._ 58.

[162] One took eight drops from Reaumur, iv. 230. PLATE VII. FIG. 5.

[163] Bartram's _Travels_, 383.

[164] i. 127. The West India sand-fly was noticed by the late Robinson Kittoe, Esq., who however did not recollect their fetching blood.

[165] See above, p. 48-49.

[166] _Travels_, &c. i. 126.

[167] See Curtis' _Brit. Ent._ t. 122.

[168] It has been generally supposed by naturalists, that the Mosquitos of America belong to the Linnean genus _Culex_; but the celebrated traveller Humboldt asserts that the term _Mosquito_, signifying a _little fly_, is applied there to a _Simulium_, Latr. (_Simulia_, Meig.), and that the _Culices_, which are equally numerous and annoying, are called _Zancudoes_, which means _long legs_. The former, he says, are what the French call _Moustiques_, and the latter _Maringouins_. _Personal Narrative_, E. T. v. 93.

[169] Plin. _Hist. Nat._ l. xi. c. 28. Aristot. _Hist. Animal._ l. i. c. 5.

[170] Pliny was aware of this double office of the proboscis of a gnat, and has well described it. "Telum vero perfodiendo tergori quo spiculavit ingenio? Atque ut in capaci, cum cerni non possit exilitas, ita reciproca geminavit arte, ut _fodiendo_ acuminatum pariter _sorbendoque_ fistulosum esset." _Hist. Nat._ l. xi. c. 2.

[171] Humboldt has described several South American species. _Personal Narrative_, v. 97. note *. Engl. Tr.

[172] Germar's _Magazin der Entomologie_, i. 137.

[173] _Philos. Trans._ 1767, 111-13. I once witnessed a similar appearance at Maidstone in Kent.

[174] Weld's _Travels_, 8vo. edit. 205. Yet Mouffet affirms the same: "Morsu crudeles et venenati, triplices caligas, imo _ocreas_, item perforantes." 81.

[175] Acerbi's _Travels_, ii. 5. 34-5. 51. Linn. _Flor. Lapp._ 380-1. _Lach. Lapp._ ii. 108. De Geer, vi. 303-4.

[176] Reaum. iv. 573.

[177] Dr. Clarke's _Travels_, i. 388.

[178] Jackson's _Marocco_, 57.

[179] _Travels_, ii. 93. Mr. W. S. MacLeay, in a letter I recently received from him, observes, speaking of his residence at the Havana; "The disagreeables are ants, scorpions, mygales, and mosquitos. The latter were quite a pest on my first arrival within the tropics; but now I mind them about as much as I did _gnats_ in England."

[180] Humboldt's _Personal Narrative_, E. T. v. 87-. Most writers by the term mosquitos mean gnats; and for them it is here chiefly employed, but may be regarded as including both plagues.

[181] Theodorit. _Hist. Eccl._ 1. ii. c. 30.

[182] Mouffet, 85. Amoreux, 119.

[183] Viz. _Mosquito_ Bay in St. Christopher's; _Mosquitos_, a town in the Island of Cuba; and the _Mosquito_ country in North America.

[184] Mouffet, 85.

[185] Deut. vii. 20. Josh. xxiv. 12.

[186] Amoreux, 242.

[187] _Philos. Trans._ i. 201.

[188] Hawkesworth's _Cook_, iii. 223.

[189] Stedman, ii. 94.

[190] Bingley, iii. 385, first edit.

[191] Knox's _Ceylon_, 24.

[192] Stedman, ii. 142.

[193] Ulloa's _Voy._ i. 61, 62. Dr. Clarke's _Travels_, i. 486. Amoreux, 197. Mr. W. S. MacLeay relates to me that soon after his arrival at the Havana he was stung by an immense scorpion, but was agreeably surprised to find the pain considerably less than the sting of a wasp, and of incomparably shorter duration.

[194] Andrews's _Anecdotes_, 427. See on the subject of Scorpions Amoreux, 41-54. 176-205.

[195] Fab. _Suppl._ 294. 2.

[196] _Catal. Ham._ 1797. 151-195.

[197] PLATE VII. FIG. 13. _a"_.

[198] Ulloa's _Voyage_, i. 61.

[199] Amoreux, 217-226. See also 67-70.

[200] p. 31.

[201] Jackson's _Marocco_, second edit.

[202] Ulloa, i. 64. Probably the _Cafafi_, a white fly noticed by Humboldt, is synonymous with this of Ulloa, which could only be prevented from creeping between the threads of the curtains by keeping them wet. _Personal Narrative_, E. T. v. 107.

[203] _Lach. Lapp._ i. 208, 209. _Fl. Lapp._ 382, 383. It appears however, from other authors, that they do bite.

[204] Young's _Travels in France_, i. 298. These flies are equally troublesome and tormenting in Sweden. See _Amœn. Acad._ iii. 343.

[205] Cowhage has been administered with success as an _anthelminthic_, as has likewise spun glass pounded; the spicula of these substances destroying the worms. The hair of the caterpillars here alluded to, and perhaps also of the larva of _Euprepia Caja_, (the Tiger-Moth,) might probably be equally efficacious.

[206] Reaum. ii. 191-5.

[207] Mouffet, 185. Plin. _Hist. Nat._ l. xxxviii. c. 9. Amoreux, 158.

[208] Amoreux, 210-212.

[209] Ulloa's Voyage, b. vi. c. 3. Hamilton (_Travels in Colombia_, as quoted in the Literary Gazette, April 28, 1827.) also mentions a spider called the _Caya_, rather large, found in the broken ground and among the rocks, from the body of which a poison so active is emitted, that men and mules have died in an hour or two after the venomous moisture had fallen on them. This is evidently the same insect with that mentioned by Ulloa, and confirms the above account of its venomous effects.

[210] Waterton (_Wanderings in S. America_, 53.) gives the recipe by which the Macousho Indians prepare the poison, in which they dip their arrows. It consists of a vine called the Wourali, which is the principal ingredient; the roots and stalks of some other plants; two species of ants, the sting of one of which is so venomous that it produces a fever; a quantity of the strongest Indian pepper (_Capsicum_), and the pounded fangs of two kinds of serpents.

[211] Tulpius, _Obs. Med._ l. ii. c. 51. t. 7. f. 3. _Edinb. Med. and Surg. Journ._ n. 35. 42-48. Derham, _Physic. Theol._ 378. note _b._ Lowthorp, _Philos. Trans._ iii. 135.

[212] _Philos. Trans._ 1665. x. 391. Shaw's _Abridg._ ii. 224.

[213] Mead, _Med. Sacr._ 105.

[214] _London Medical Review_, v. 340.

[215] _Philos. Trans._ ubi supra.

[216] Fulvius Angelinus et Vincentius Alsarius _De verme admirando per nares egresso_. Ravennæ 1610.

[217] Azara, 217. I cannot help suspecting this to be synonymous with the _Œstrus Hominis_ next mentioned.

[218] From Pallas _N. Nord. Beytr._ i. 157.

[219] _Essai sur la Géograph. des Plantes_, 136.

[220] Clark in _Linn. Trans._ iii. 323, note.

[221] Leeuw. _Epist._ Oct. 17, 1687.

[222] _Edinb. Med. and Surg. Journ._ ubi supra. De Geer, vi. 26, 27.

[223] 216.

[224] Lempriere _On the Diseases of the Army in Jamaica_, ii. 182.

[225] In passing through this parish last spring, I inquired of the mail-coachman whether he had heard of this story; and he said the fact was well known.

[226] _Philos. Mag._ ix. 366.

[227] Bonnet, v. 144.

[228] _Mém. Apterolog._ 79.

[229] _Universal History_, iv. 70. Ed. 1779.

[230] Wisd. xvii. 12.