Part 32

But the pregnant female leaves all these dimensions far behind. Her abdomen becomes two thousand times as big as the rest of her body! She then attains to six inches in length, and weighs as much as thirty thousand workers. By a hideous contrast, the head alone does not increase in size. D D D D (Fig. 383) is an exact representation of this monster. She is always motionless and captive in her cell, entirely occupied in laying. Her fecundity surpasses all bounds: sixty eggs a minute, more than 80,000 a day. Smeathman is inclined to think that this prodigious laying goes on during the whole of the year. "This soft, whitish beast," says M. Michelet, "a belly rather than a being, is as large, at least, as one's thumb; a traveller professes to have seen one of the size of a crawfish. The larger she is, the more fruitful, the more inexhaustible, this terrible insect-mother seems to be the more adored by the fanatical rabble. She seems to be their beau ideal, their poetry, their enthusiasm. If you carry away with any rubbish a portion of their city, you see them instantly set to work at the breach to build an arch which may protect the venerated head of the mother, to reconstruct her royal cell, which will become (if there are sufficient materials) the centre, the base of the restored city. I am not astonished, though, at the excessive love which this people show for this instrument of fecundity. If all other species did not combine to destroy them, this truly prodigious mother would make them masters of the world, and--what shall I say?--its only inhabitants. The fish alone would be left; but insects would perish. It suffices to be remembered that the mother-bee does not produce in a year what the female white ant can produce in a day. By her they would be enabled to devour everything; but they are weak and tasty, and so everything devours them."[112] In fact, birds are very greedy after termites; poultry destroy immense quantities of them. Ants give chase to them and eat them by legions. The negroes in Southern Africa cannot be sated with them. They gather such as have fallen into the water, and roast them like coffee; thus prepared, they eat them by handfuls, and find them delicious. The Indians smoke the termites' nests, and catch those that have wings. They knead them up with flour, and make a sort of cake of them. Travellers, moreover, all agree in speaking of them as very nice food, comparing their flavour to that of marrow or of a sugared cream. Smeathman prefers them to the famous palm worm (_ver palmiste_ of the colonists), a delicacy known in South America, which is the larva of the _Calandra palmarum_, a species of beetle. It seems, however, that an abuse of fried termites brings on a dysentery which may prove mortal.

[112] J. Michelet, "L'Insecte," p. 328.

All the species of termites are miners, but the greater number are also architects and masons. A few make their nests round a branch of a tree. This nest is of enormous dimensions: it is as large as a tun. The illustration (PLATE X.)--after a drawing in Smeathman's work--shows a nest of the _Termes bellicosus_, composed of bits of wood firmly stuck together with gum. Above their subterranean galleries the greater part of termites construct vast edifices, which contain their magazines and nurseries. The _Termes mordax_ and _Termes atrox_ raise perfect columns, surmounted by capitals which project beyond them and give them the appearance of monstrous mushrooms. These columns attain a height of twenty inches, with a diameter of five; they are constructed with a black clay, which, worked up by the insects, acquires great hardness. The interior is hollow, or rather perforated with irregular cells; but the most curious edifices are those of _Termes bellicosus_. These are irregularly conical mounds, flanked by a certain number of turrets, decreasing in height. Smeathman gives them a height of from ten to twelve feet; but Jobson[113] affirms that he has seen some as high as twenty feet. If men constructed monuments so disproportionate to their size, the great pyramid of Giseh, instead of being 146 mètres in height, would be 1,600, and would be higher than the Puy-de-Dôme!

[113] "History of Gambia."

These knolls of earth are of a solidity which will bear any trial. Not only can many men mount on them without shaking them, but buffaloes establish themselves upon them as watch-towers, from which they can see over the high grass which covers the plain, if the lion or the panther is threatening them. These edifices are hollow; but their sides are from fifteen to twenty inches thick, and are as hard as a rock. They are hollowed out into galleries, which connect them with the underground dwelling. Under the dome is a pretty large vacant space, a sort of top storey or attic, occupying one-third of the total height, and which keeps up in the edifice a more uniform temperature than if all the block had been filled up. On a level with the ground is the royal cell, oblong, with a flat floor and a rounded ceiling, and pierced with round windows. All round are distributed the offices; they are rooms also with rounded and vaulted ceilings, communicating with each other by corridors. On the sides rise the magazines, with their backs placed against the walls of the house; they are filled with gums and with vegetable juices solidified and in powder. On the ceiling of the royal chamber rise pillars of about two feet in height, which support the egg rooms. These are little cells with partitions of saw-dust stuck together with gum, which separate at the opening the large chambers from the clay halls. Placed between the attics and the great nave surmounting the royal hall, the nursery is in the most desirable position possible for uniformity of temperature and for ventilation.

The royal cell encloses a unique couple, objects of the most assiduous attentions, but kept in closest captivity, for the doors are too narrow to afford a passage to the monstrous queen, and even to the male, who keeps generally crouching by her side. Thousands of servants busy themselves round the mother; they feed her and carry away, night and day, the myriads of eggs which she lays. The eggs are placed in the egg houses, where they give birth to white larvæ, resembling the workers, which nourish themselves at first on a sort of mouldy fungus which grows on the partitions of their cells. They then become pupæ, then neuters, or males and females, the last two being provided with wings.

On a stormy evening the males and females come out of their nest by millions to couple in the air; then immediately afterwards they fall to the ground and lose their wings, when they become an easy prey to their enemies. A few couples only, picked up by the workers, are put under shelter, and become the nucleus of a new colony. The soldiers have no other occupation but to defend the nest. If man attacks them, at the first blow with the pick-axe they are to be seen running out furiously. They attack their aggressors, pierce them till they bring blood, and with their sharp pincers hang on to the wound, and allow themselves to be torn to pieces rather than leave go their hold. The negroes who have no clothes are soon put to flight; Europeans only get off with their trousers very much spotted with blood. During the combat, the soldiers strike from time to time on the ground with their pincers, and produce a little dry sound, to which the workers answer by a sort of whistling. The workers immediately make their appearance; and with their pellets of mortar set to work to stop up the holes, and to repair the damage. The soldiers then re-enter, with the exception of a small number, who remain to superintend the work of the masons; they give, at intervals, the usual signal, and the workers answer by a whistling which means, "Here we are!" as they redouble their activity. If the attack recommences, the soldiers are at their posts, defending the ground inch by inch. During this time the workers mask the passages, stop up the galleries, and wall up with care the royal cell. If you manage to penetrate as far as this sanctuary, you may pick up and carry away from the cell which contains them the precious couple without the workers in attendance on them interrupting their work, for they are blind.

They never venture in sight except in extreme cases. No one is ignorant of the terrible destruction these insects occasion to the works of man. Invisible to those whom they threaten, they push on their galleries to the very walls of their houses. They perforate the floors, the beams, the wood-work, the furniture, respecting always the surface of the objects attacked in such a manner that it is impossible to be aware of their hidden ravages. They even take care to prevent the buildings they eat away from falling by filling up with mortar the parts they have hollowed out. But these precautions are only employed if the place seems suitable, and if they intend to prolong their sojourn there. In the other case they destroy the wood with inconceivable rapidity. They have been known, in one single night, to pierce the whole of a table leg from top to bottom, and then the table itself; and then, still continuing to pierce their way, to descend through the opposite leg, after having devoured the contents of a trunk placed upon the table. On account of the devastations which they occasion, Linnæus has called the white ant the greatest plague of the Indies.

There exist in France two species of termites, the _Termes lucifugus_, a little insect of a brilliant black (at least in the male), with russety legs, which is common enough in the moors of Gascony; and the Yellow-necked White Ant (_Termes flavicollis_), which lives in the interior of trees and does a great deal of mischief in Spain and in the south of France to olive and other precious trees, whilst the first attacks oak and fir trees. Latreille established that it is the _Termes lucifugus_ which causes such havoc at La Rochelle, at Rochefort, at Saintes, at Tournay-Charente, in the Isle of Aix, &c., where many houses have been completely undermined by these terrible insects. But M. de Quatrefages[114] has proved that the habits of the termes found in towns differ in many essential points from the habits of termes in the country. And so it is most probable that the former belong to an exotic species, which must have been unfortunately imported into France by a merchant vessel. According to M. Bobe-Moreau,[115] it was only in 1797 that termites were discovered for the first time in Rochefort, in a house which had stood for a long while uninhabited, and which they had completely undermined. In 1804, Latreille relates, as a "hearsay," that the termites had for some years made the inhabitants of Rochefort uneasy; but in 1829 the same author tells a very different tale. He speaks with dismay of the ravages committed by this insect in the workshops belonging to the Royal Navy. The importation of the termes into France is then of recent date. A note which was sent to M. de Quatrefages by M. Beltrémieux, fixes with still greater accuracy the date of the importation of the termites; it must have taken place about 1780, a period at which the brothers Poupet, rich shipowners, caused bales of goods to come from St. Domingo to Rochefort, to La Rochelle, and to other places in that neighbourhood which possess storehouses. The ravages which the termites have committed in the towns of La Saintonge are really frightful. Like Valencia, in New Granada, these towns will find themselves one of these days suspended over catacombs. At Tournay-Charente, the floor of a dining-room fell in, and the Amphytrion and his guests tumbled together in the cellar. There may be seen in the galleries of the Museum of Natural History of Paris the wooden columns which supported this room, and which were preserved by Audouin, who had been sent on a mission to report on the damages done. Audouin also selected, as an object of curiosity, a lady's bridal veil, which had been entirely riddled with holes by the termites.

[114] "Note sur les Termites de la Rochelle." _Annales des Sciences Naturelles_, 3e série, tome xx., p. 18. 1853.

[115] "Mémoire sur les Termites observés à Rochefort." Saintes, 1843.

At La Rochelle these insects took possession of the Prefect's house (built by the brothers Poupet), and of the Arsenal. There they invaded offices, apartments, court, and garden. They could not drive in a stake, or leave a plank in the garden, but it was attacked the next day. One fine morning the archives of the department were found destroyed, without there being the smallest trace of the damage to be seen on the exterior. The termites had mined through the wood-work, pierced the cardboard, eaten up the parchments and the papers of the administration, but had always scrupulously respected the upper leaf and edges of all the leaves. It was by mere chance that a clerk, less superficial than his colleagues, one fine day raised one of the leaves which hid this _detritus_, and thus discovered the destruction of the archives. All the papers of the Prefecture are now shut up in boxes of zinc.

These termites do not venture, any more than their congeners, into the light of day. These terrible miners always envelop themselves in obscurity, and construct on all sides covered galleries as they advance into a building. M. Blanchard and M. de Quatrefages saw in La Rochelle the galleries made by them. They are tubes formed of agglutinated material, which are stuck along the walls in the cellars and the apartments, or else suspended to the roof like stalactites. Certain parts of Agen and of Bordeaux begin also to suffer from the ravages of these insects. The danger appears to be imminent.

We are indebted to M. de Quatrefages for some interesting experiments on the termites of La Rochelle. Not only has the learned naturalist helped to make known to us the habits of these dark-loving insects, but he has also told us how to destroy them. Different substances have been tried in vain to stop these terrible ravages--essence of turpentine, arsenical soap, boiling lye, &c. M. de Quatrefages had recourse to gaseous injections. He tried successively binoxide of nitrogen, nitric acid, chlorine and sulphurous acid; chlorine, above all, fully answered his hopes. With pure chlorine he killed the termites instantaneously; mixed with nine-tenths of air, he suffocated them in half an hour. "For attacking the termites," says M. de Quatrefages, "one ought to choose by preference the period of their reproduction, so as to destroy the pregnant females. It is probable that, like their exotic congeners, the termites of France will endeavour to defend themselves by walling up the interior of their galleries at the first signs of an attack. The operator must then act with a great deal of promptitude, and direct the apparatus as much as possible into the very centre of their habitation, where the galleries are the broadest and the most numerous.

"With whatever care one acts, and whatever may be the success of a first attempt, it seems to me impossible to destroy in one campaign all the termites of a locality. In this, as in all operations of the same kind, a certain amount of perseverance is necessary, especially if it is in a town or in a country infested by them to a very great degree; in that case one will be forced to repeat the operation from time to time. When, on the contrary, the termites are already cantoned, it seems to me that the success ought to be lasting. This is fortunately the case at La Rochelle; and by knowing how to profit by it, one may doubtlessly prevent the spread of these pests, which at one time or another, may attack the whole town."[116]

[116] "Mémoires sur la destruction des Termites." _Annales des Sciences Naturelles_, 3e série, tome xx., p. 15.

In 1864 the Lords of the English Admiralty addressed an inquiry to the Entomological Society of London, on the best means of preserving wood from the attacks of the Indian termites. In answer to this inquiry, the Entomological Society recommended many processes: the injection of quicklime or of creosote, the application of arsenical soap, &c. But it does not appear that these processes are infallibly efficacious, nor, above all, easy to employ.

Among other Neuroptera which undergo incomplete metamorphoses, we may mention, first, the genera _Perla_ and _Nemoura_,[117] (Figs. 384, 385, and 386), which flutter about the banks of rivers, and settle on stones, shrubs, and aquatic plants. Their larvæ are naked, without cases, and always live in the water, hiding themselves under stones, to watch for small insects, for they are carnivorous. One sees them often balancing their bodies, holding on to a pebble. They go through the winter, and only become pupæ in the spring. After moulting, they have the rudiments of wings. Very soon afterwards the pupæ leave the water, and undergo their metamorphosis. The adult lives only a few days, for its mouth is not suited for receiving food. The larvæ have, at the end of their bodies, two long threads, which remain in the perfect _Perla_, but not in the perfect _Nemoura_; the latter lose the two caudal hairs when they arrive at the adult state. One species of _Perla_ is very common on the quays of Paris.

[117] From [Greek: nêma], a thread; and [Greek: oura], a tail.--ED.

The _Ephemeridæ_, or May-Fly family, have long, slender bodies, provided with two or three long silky hairs. Their name indicates the short duration of their existence. They appear in great numbers at certain seasons of the year. Their hatching takes place at sunset; they have coupled and laid their eggs by sunrise next day, and have ceased to live; so that the banks of rivers, of ponds, of lakes, are strewed with their bodies. Their number is sometimes so considerable that, according to Réaumur, the soil seems as if it were covered with snow, and they are gathered up for manure. The common Ephemera, or May-Fly (_Ephemera vulgata_, Fig. 390), is of a brown colour, banded with yellow, and the wings smoky, with brown spots. These insects are remarkable for their elegant flight; they are continually rising and falling. When they move their wings they rise; but if their wings, though spread out, remain motionless, as also the silky hairs which form their tail, they fall again. They may be seen in myriads in places where there is much water.

We have said that the _Ephemeræ_ live only for a few hours. This is the general rule; but their existence can be prolonged for ten or fifteen days by preventing their copulation. If, however, the duration of the life of these insects is so short when they have reached the perfect state, and when the conformation of the mouth prevents them from taking any nourishment, their larvæ state is of very long continuance. Swammerdam says, in his curious Memoir, entitled "Vita Ephemeri," it is not less than three years.

The females lay their eggs in one single mass, and let them fall into the water, in the form of a packet. The larvæ which come out of them are very active, and swim with great ease; but generally conceal themselves under the pebbles at the bottom. The sides of their abdomen are provided with gills, very much fringed, which serve them, not only for breathing the air under the water in the same way that fish do, but also for swimming. The larvæ have, at the extremity of their body, two or three hairs, like the perfect insect. They hollow out galleries in the beds of rivers and ponds, and live on small insects. The pupa (Fig. 392) differs only from the larva (Fig. 391) in having the rudiments of wings. When about to undergo their metamorphosis, they come out of the water and cling to plants, &c. The skin cracks on the back when it is dry, and there comes out a heavy insect, which flies feebly, and has opaque wings. It is still enveloped in a very thin skin, of which a last moult, after a few hours, frees it. This skin remains sticking to the plant on which the moulting was effected, preserving the shape of the insect. This moult is peculiar to the _Ephemeræ_; it is the transition from the false imago (pseudo-imago) to the imago.

In the same family is the genus _Cloëon_, whose larvæ prey on minute insects. The _Cloëon diptera_ (Fig. 393), which has only two wings, is often to be met with in houses, resting on the window panes and curtains. All these insects keep badly in collections; they lose their shape, and their members are so fragile that the least shock suffices to break them.

The _Libellulas_, or Dragon-Flies, are insects of a well-defined type. The elegance of their shape, the grace of their movements, have won for them among the French their common appellation of "Demoiselles." They are always of largish size. Many are of bright and metallic colours, which are not inferior in beauty to those of butterflies. Their wings, of an extreme delicacy, always glossy and brilliant, present varied tints; sometimes they are completely transparent, and have all the colours of the rainbow. Often, the colour of the males differs from that of the females. They may be seen fluttering about on the water during the whole summer, especially when the sun is at its highest. They fly with extreme rapidity, skimming over the water at intervals, and escaping easily when one wishes to catch them. Nothing is prettier than a troop of dragon-flies taking their sport on the side of a pond or on the banks of a river, on a fine summer's day, when a burning sun causes their wings to shine with most vivid colours.