Part 52
[158] Lettsom’s Naturalist’s Companion; Curtis’s Instructions for Collecting and Preserving Insects. Both these tracts are now become very scarce.
Of all the different classes or orders of insects, that called LEPIDOPTERA is not only one of the most numerous, but the most beautiful, with respect to the variety as well as richness of their colours; and, as from the peculiar delicacy of their structure, they require greater care to be used in catching, as well as in preserving them, it will be proper first to speak of, and be more particular in the directions concerning them.
THE METHOD OF PROCURING MOTHS AND BUTTERFLIES.
There are two methods of collecting insects of this kind; first, by breeding; secondly, by catching them in their fly state: of these, the former is by much the preferable mode; as, besides the pleasure which arises from observing the gradual progress of the insects from their egg or caterpillar to their perfect or fly state, they may be killed before they have sustained the smallest injury in the farina or meal of their wings by flying.
The difficulty likewise in procuring the most beautiful and valuable insects of this class in their fly state, renders this method by far the most eligible. Most of the sphinges of Linnæus, or, as they are usually called, hawk-moths, are but seldom met with in their fly state, and when seen on the wing, generally elude the swiftest pursuit; but in their caterpillar state they are frequently found, and easily taken. Thus the caterpillar of the sphinx atropos or jasmine hawk-moth, the largest and most beautiful species of moth this country produces,[159] is often found feeding on the jasmine and potatoe, and sometimes on green elder; the sphinx elpenor or elephant hawk-moth, on the Galium palustre or white ladies-bed-straw; the sphinx ocellata or eyed hawk-moth, on the willow and apple-trees; sphinx tiliæ or lime hawk-moth, on the lime-tree; sphinx lagustri or privet hawk-moth, on the privet; phalæna pavonia or emperor-moth, on the briar, black-thorn, willow, &c. and so of a great number of others.
[159] Desirous as every collector must be of obtaining these moths, it is certain there are many persons still existing, who would consider it as a great calamity were one of them to fly into, or even approach their habitation; and so far from affording the pretty fugitive an asylum, would experience the highest satisfaction at his speedy departure. The reason, if it be not a prostitution of the term, is, that as the plumage on the back of this moth exhibits somewhat of the resemblance of a death’s head, these intelligent prognosticators (naturalists they cannot be called) are fully convinced that this harmless insect must be the harbinger of mortality, and that its appearance infallibly portends speedy death to some one of the family! Indeed, to weak minds, especially if previously debilitated by sickness, such an idea, if permitted to prey upon their spirits, may be productive of fatal consequences, and thus stamp a credit on the prophetic abilities of those sagacious observers of the mysteries of nature. To medical men, who are daily witnesses of the wonderful influence which the mind possesses over the body in a diseased state, such events do not appear at all surprizing.
THE METHOD OF COLLECTING MOTHS, &C. IN THEIR CATERPILLAR STATE.
Independent of the method of collecting caterpillars by an attentive examination of the leaves, and other parts of plants, at those times of the year when they are in full verdure, there is another, viz. by beating the boughs of trees, particularly the taller ones, with long poles, having previously spread a large sheet underneath to receive them as they drop from the trees. By these means many very valuable caterpillars are frequently obtained, which could not otherwise be procured without considerable difficulty. Caterpillars should be handled as little as possible, particularly those with smooth skins; the more hairy ones in general sustain less injury by it. To convey them home with safety, the collector should be provided with a chip box in his pocket; and it would be proper to have it partly filled with fresh leaves.
THE METHOD OF REARING OR BREEDING THEM.
Having procured the caterpillars, our next endeavour must be to rear them. For this purpose; it will be indispensably necessary to afford them an ample supply of the plant on which they are found feeding, and to renew their food as often as the decay of that first procured for them may render it expedient. Insects in this state usually feed voraciously; the caterpillar of the papilio brassica has been known to consume in one day twice its own weight of food. Although many of them live on a variety of food, the greatest part are attached to some particular kind; deprived of which, some species would form objects less beautiful when arrived at their perfect state, and others infallibly perish.
As to many it may prove very inconvenient to supply the caterpillars with fresh food daily, to avoid this trouble, several sprigs of the tree or plant may be put into a wide-mouthed glass filled with water, and the caterpillars placed on them. Most plants may in this manner be preserved fresh for three or four days. The glass, together with the caterpillars and their food, is to be placed in the breeding box represented in the figure annexed, _a_, shews an opening in the front covered with gauze; _b_, the door on the side; _c_, a ring for conveniency of carriage; and a constant supply of fresh food is to be given them, as soon as the former appears in the least withered. The breeding boxes should never be exposed to the scorching rays of the sun, but placed in a cool and shady situation; nor should they contain more than one kind of caterpillar, as some species devour others.
When arrived at their full growth, the caterpillars leave off eating, and soon after, change into the chrysalis or pupa form; previous to which, butterflies spin a little web, just sufficient to suspend themselves by: many of the moths, like the silk-worm, spin a large web, in which they inwrap themselves; and a great number penetrate into the earth, where they spin themselves cases, or change without any spinning, as do most of the sphinges or hawk-moths. It will therefore be necessary to cover the bottom of the box with fine mould to the depth of four or five inches, and keep it constantly moist.
It frequently happens that caterpillars are what the aurelians call stung, that is, have the eggs of the ichneumon-fly deposited in them, of which operation a full account has been given in pages 295-298. Caterpillars, previous to their going into the chrysalis state, generally lose the brilliancy of their colours, and many of them rove about for some time.
After remaining in their chrysalis state till near the time of their coming forth, such as are inclosed in a hard case or spinning, as the phalæna vinula, puss moth; phalæna quercus, great egger moth, &c. are to be carefully freed from it; as the aperture which the insect naturally makes is often too narrow for it to pass through without sustaining considerable injury in its plumage. The opening will be best made, by cutting off the larger extremity of the case, taking especial care not to wound the inclosed pupa or chrysalis.
The learned Dr. Bellardi, Foreign Member of the Linnean Society, &c. a few years since discovered a new method of feeding silk-worms, when they are hatched before the mulberry-trees have produced leaves, or when the tender branches are destroyed by frost: how far this practice may be successfully applied in other instances, seems as yet undetermined; though from some recent experiments, it appears possible that caterpillars may be thus fed in backward seasons. This method consists in giving the caterpillar-the dried leaves of their accustomed food reduced to powder, and gently moistened with water; a thin coating of which must be placed round the young worms, who will immediately begin to feed upon it. The Doctor informs us that the caterpillars of the silk-worm prefer it to any other food, and devour it with the utmost avidity. The leaves should be gathered towards the close of the autumn, before the frost commences, in dry weather, and when the heat is greatest; they must be dried in the sun by spreading them upon large cloths, and after being reduced into powder, laid up in a dry place. Donovan says,[160] that the experiment has been tried with several caterpillars which were nearly full fed on the leaves of thorns and oaks thus prepared, and that they were observed to eat it when no other food was given, but he cannot determine how far they may thrive if fed on that aliment only.
[160] Treatise on the Management of Insects.
THE METHOD OF COLLECTING THEM IN THEIR CHRYSALIS STATE.
Butterflies and moths may often be found in chrysalis under the projection of garden walls, pales, out-houses, in summer-houses, &c. and frequently affixed to the food on which the caterpillar fed. A great variety of moths in the pupa state may with more certainty be found, during the winter months, by digging under the trees on which they feed, particularly under the oak, willow, lime, and elm trees. When they are procured in this manner, they should be placed as soon as convenient in the breeding box before described, and kept covered with moist earth till the ensuing spring; when, as soon as the weather is mild, they may be dug up and placed somewhat nearer the surface of the mould, and in that manner left to come out of themselves. Should the collector not succeed in procuring chrysalides by this method, it will frequently happen that his labour will be amply recompensed by obtaining a variety of beetles.
THE METHOD OF COLLECTING THEM IN THEIR FLY OR PERFECT STATE.
The extreme delicacy of the wings of moths and butterflies will not admit of their being caught without injury, but in nets made of the finest materials. It will be necessary, therefore, that the collector should provide himself with a net properly adapted to this purpose: the one here represented has, after long experience, been found to answer extremely well. Fig. A shews the net expanded ready for use; _a_ exhibits the part made of fine Scotch gauze, which should be previously dyed green; _b_ _b_, the sticks; these should be of some light wood. To render them compact and convenient for carriage, they are made to take to pieces somewhat in the manner of fishing-rods, and connected by means of screws or hollow brass ferrils fixed to the end of each: there are three of them for each side of the net. Fig. B shews one of the sticks; _a_, the brass ferril; _b_, the end of the next stick, which fixes tight into it; to the upper end of the sticks, at _c_, is joined in like manner a piece of cane bent to a proper shape. Instead of three pieces of wood, as here described, the other stick may consist of one entire piece, and be used as a walking-stick. The gauze must be edged with two pieces of binding sewed together, to receive the sticks when joined; and, as the sticks are taper, so must be the cavity to receive them. At the lower part the gauze is to be turned up about six inches, so as to form a bag, Fig. A, _c_. At the extremity of the gauze, next the handles, two pieces of tape must be fixed on each side, _d_ _d_, of sufficient length to pass through a hole bored in the stick, and then be tied in a loop, so as to prevent the gauze from sliding on the sticks. At the upper part of the net where the canes meet, _e_, the cavity should be closed by a few stitches, that the sticks may shut even together. The net may be about a yard in width when expanded, and the length of it a yard and an half: the size, however, may be varied at pleasure. The gauze should be deprived of its glazing by being soaked for a short time in warm water; but, if dyed green, which is usually the case, this will be unnecessary. The handles are to be held one in each hand, when the net is used.[161]
[161] Though this net be principally intended for catching moths and butterflies on the wing, it maybe usefully applied to another purpose: if one person expand the net under a bush or branch intended for examination, and another shake the bush, or beat it well with a stick, numbers of caterpillars, as well as some of the minuter kinds of coleopterous, and other insects, will fall into the net. By these means moths are likewise often taken, as they remain in a torpid state during the day, sheltered in the bushes.
Besides the gauze net for catching butterflies, &c., the collector should be provided with a pair of forceps, made of steel, about nine or ten inches in length, and of the shape represented in the figure;[162] the fans are to be covered with fine green gauze. This instrument will in many instances be found exceedingly commodious, as being of more general use; it is very portable, and possesses this advantage over the net, that the insect caught in it will be more confined, and consequently not so liable to injure its down. If the insect be met with on the trunk of a tree, paling, or any flat surface, it may be readily caught; if on a leaf, both may be enclosed in the forceps. Whilst in the forceps, it should be pressed with the thumb, or, if the creature be small, with the thumb-nail, sufficient to stupify, but not crush it.
[162] This figure shews the forceps in the proportions in which they have been generally made; I would, however, recommend the fans to be considerably larger, and the handles shorter. The form of the fans has commonly been either hexagonal, or, the worst of all, triangular; experience has taught me that the shape as here given is to be preferred, as being less liable to miss the insects, who are usually upon their guard, and frequently elude the vigilance of their pursuers. A front view of the fans is given, the better to shew their form; but it is obvious that they must be placed in a contrary direction, so as to flap on, not slide over, each other.
The next articles necessary to be provided, will be two or three oval chip boxes, cut sufficiently flat for the pocket, and lined at top and bottom with thin cork; and a cushion well stored with pins of various sizes.
The collector being now furnished with the necessary instruments, it will be proper to give him such instructions as may enable him to use them. With regard to the manner of using the net with expertness and success, this knowledge will be much better acquired by practice than by the most ample description. Harris, in his elegant work, The Aurelian, has been rather diffusive than clear on this subject. Having caught the butterfly or moth in the net, it will be necessary to proceed with caution, as on killing it properly its beauty in a great measure depends. It should not be laid hold of indiscriminately in any part; but by managing skilfully the net, its wings must, if possible, be brought into an erect position or close together; then press the under part of the thorax or breast between the thumb and the fore-finger sufficiently hard to kill the insect. By carefully attending to these directions, the wings will not be distorted or the plumage injured.
The net being now opened, the insect is to be laid hold of by one of its antennæ or horns, and again placed between the thumb and fore-finger; in which situation it is to be held, while a pin proportioned to its size is stuck through the upper part of the thorax or back; it may then be affixed to the pocket-box by sticking the point of the pin into the cork lining. The larger kinds of these insects, especially moths and hawk-moths, which are far more tenacious of life than butterflies, will not expire so readily by this method, as by fixing them upon the bottom of a cork exactly fitted to the mouth of a bottle into which a little sulphur has been put; by gradually heating the bottle till an exhalation of the sulphur takes place, the insect usually dies without injuring its colour or plumage.
THE METHOD OF MANAGING THEM IN THEIR FLY STATE.
Though by the means just described these insects may be caught uninjured, some farther care is requisite in order to make them appear to advantage; this is called setting them, and is performed in the following manner. The insect being stuck through with a pin of a proper size, is to be placed before its wings are become stiff, on a piece of cork, having a smooth surface and covered with white paper. The body of the fly should not be made to touch the cork when the insect is affixed to it, but to stand up some little distance from it, as only the edges of both wings are intended to touch, not the wings to lie flat on the cork. The wings are then to be expanded, as in the figure, with a fine needle, or some sharp-pointed instrument. The instruments used in the operation for the eye called couching, being fixed to taper handles, are peculiarly commodious for this purpose.
The upper edges of the superior wings are to be placed in a line with the head of the insect, and they are to be kept in this situation by means of little braces, formed of card-paper and cut in the shape represented in the figure; a number of which should always be kept in readiness in a small box. These must be proportioned to the size of the wings, and fitted to their shape, by being more or less bent; by a proper attention to which, the spots, &c. on both wings are rendered conspicuous, and the beauties of the insect exhibited in full perfection. To acquire the method, however, of setting them well, requires considerable practice and some ingenuity. After remaining in this position four or five days, or till the insect is become thoroughly stiff, the braces may be taken off, and the insect removed into the store box. The shape of the store box is immaterial; it should, however, be flat, and may be made either of wood, or, which is preferable, of tin. The inside should be lined with thin cork and covered with paper, and some slips of cloth glued to its edges to make it shut closer, and thus exclude as much as possible insects and animalcula; a little camphor tied in a bit of rag, and pinned to a corner of the box, will be found very useful to prevent their depredations.
It is particularly to be observed, that there is a continual succession of insects as well as of plants; some appear with the early primrose, others accompany the late-flowering ivy: so that in this respect, the aurelian and entomologist may regulate their excursions by those of the botanist; the latter would in vain search for the ranunculus ficaria or pile-wort, in the month of July, and the former be equally disappointed in seeking for the papilio cardamines, orange-tip, in the month of August.
Some of these insects continue longer in their fly state, and their plumage is less injured by flying, than others; some continue for a few days only; others, several weeks. In general, moths and butterflies, unless they are caught the first day of their coming out of chrysalis, are of small value; hence arises the necessity of carefully watching those particulars, and of making frequent excursions in order to obtain them in the greatest perfection.
Butterflies are to be caught on the wing only when the sun shines warm. They inhabit a variety of places; the greatest number of them frequent woods, and may be taken in or near them, as the papilio iris, purple emperor; papilio hyperantus, ringlet; and most, if not all the fritillaries. Some delight in meadows, as the papilio jurtina, meadow brown; galathea, marbled white; C. album, comma; rhamni, brimstone: and others frequent gardens, as the brassicæ and rapæ, large and small garden white; others, again, clover fields, corn fields, heaths, lanes, &c. Many of those which frequent woods are taken with much greater facility in the morning, a few hours after sun-rise; at which time they are found feeding on the flowers that grow by the sides of the woods; afterwards, when the sun shines with greater strength, they fly high, and with such rapidity, as not to be taken but with the utmost difficulty.
Moths fly chiefly in the evening, a little after sun-set. Like butterflies, they inhabit a variety of places, and are to be met with in the greatest plenty near woods; they may also be taken in great numbers in the day-time by beating the hedges, &c. more particularly in the afternoon, as the least motion will then put them on the wing. They are likewise frequently met with in the day-time sticking to the bark of trees, on walls, and pales that surround gardens, &c. and may be thus caught in great perfection. Some few, like the butterflies, fly in the middle of the day, when the sun shines warm, over the flowers of honey-suckles, and other plants with tubular flowers. Insects of this species seldom sit to feed, but continue vibrating on the wing while they thrust their tongue or proboscis into the flower.
Geoffroy says that moths may be taken in great plenty by means of a candle or lanthorn carried into or near some wood, towards dark. Independent of the recommendation of authority so respectable, the well-known propensity that moths have to fly towards, and even into candles, has induced some collectors to adopt this method with success; many of the most valuable caterpillars have also been thus obtained.
THE METHODS OF COLLECTING INSECTS OF THE BEETLE KIND.
By these are meant all such, as are included in Linnæus’s first order of insects, under the term COLEOPTERA; these have generally been called scarabæi or beetles: some few of them have obtained distinct English names, as the chaffer, lady-bird, earwig, &c. and all have been divided by Linnæus into genera and species.
The insects of this, as well as the preceding and following order, may be found in their caterpillar or grub state, in which they often prove extremely destructive to the roots of plants; and may in like manner be brought to their perfect or fly state, regard being had to their different manner of feeding. The time and care, however, required for this purpose, is probably more than can be spared by the generality of collectors; the curious entomologist, possessed of both leisure and abilities to engage in the pursuit, will be enabled to establish with certainty the different genera of insects. These insects are generally collected in their fly state: some creep and fly in the day-time when the sun shines warm; others, like the moth, fly in the evening and the night only.