The insect that had produced the perforations observed in the balls sent to the Crimea in 1854, and which M. Dumeril parUcularly studied, was the Sirex Juvencus, one having been taken from France in the wood forming the boxes containing the cartridges. In the other case of which we are speaking, that is to say, of the cartridges which were sent in 1861 to the Academie by Captain Heriot and by M. Bouteille, the perforations had been produced by other species. M. Milne-Edwards, who found the insect that had caused this strange damage, had no trouble in recognising it as the Sirex gigas, which, in its larva state, lives in the interior of old trees or pieces of wood, and which, after it has gone through all its metamorphoses, comes out of its retreat to reproduce its kind. To clear themselves a passage, they cut away with their mandibles the ligneous substances or other hard bodies they meet with on their road. It was in pursuing this object that the insects, imprisoned accidentally in the packets of cartridges when they were yet only in the larva state, must have attacked the leaden balls, as also the paper and the other matters which they met with on their road, and which opposed their passage. M. Bouteille proves, in his Memoir, that M. Dumeril has committed an error in saying that the perforating organ employed by the Sirex to attack the leaden balls in the cartridges in the Crimea was the auger situated at the extremity of the abdomen of the female, and intended for cutting into that part of the wood where it is to lay its eggs. M. Bouteille has established, in fact, that they were not only the females which attacked the cartridges, but that the males, which have no auger, had occasioned the same damage.

The TentJiredinetce are called "Saw-Flies," because the females are furnished with a double auger, notched like a saw, with which they cut into the branches in which they lay their eggs. The larvae

399

H YMENOF TERA.

of these insects have a striking resemblance to the caterpillars of Lepicloptera. They can only be distinguished from them by a great globular head, not hollowed out, and by their abdominal legs, in

Fig. 379.— Larva of a Saw-Fly. {Tenthredo). Fig. 380.— Lophyrus pini

general to the number of more than ten. They are called false caterpillars (Fig. 379). Most of them, when touched, erect themselves and move about in a threatening manner. They spin a silken cotoon before changing into pupae. The Lophyrus pini, which devours the leaves of pine trees, belongs to this family (Fig. 380).

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VII.

THYSANOPTERA.

The very small black flies which are such a source of annoyance to travellers in' the summer-time, and which fly into our eyes and crawl over our faces during the prevalence of warm windy weather, princi-! pally belong to a kind of insect which is characterised by having very I remarkable wings when in the adult condition. These insects exist: by myriads, and there are several species of them; and they are all exceedingly destructive to flowers, and especially to the bloom ol cereal plants. The little black insects are to be seen on almost every flower, and they devour the delicate cellular tissues of the

Figs. 381, 382.— The Adult Insect and Larva of Thrips cetealium (magnified).

petals. Thrips cerealium is very destructive when it occurs in multitudes upon the wheat, barley, and oats, for it interferes with the proper nutrition of the grain, by nibbling the protecting envelopes and the tissue which connects it to the stalk.

All the members of the genus Thrips — and they alone constitute the order now under consideration — possess four very narrow membranous wings, without any folds or network upon them, but furnished and decorated with beautiful fringes upon the edges. These fringes i

THYSANOPTERA. 4OI

characterise the Order, which m other respects is closely allied to the Orthoptera, and they give the name to it. The Thysanoptera {Qvawoi, fringe; TrrepoV, a wing) have filiform antennae and very large eyes, and the different species of the genus Thrips have a great diversity of wing fringing. The structure of the wings is somewhat analogous to that observed in the Lepidoptera, in the Pterophorina and the Alucitina (Fig. 381).

The metamorphoses of the Thysanoptera have not received much attention, but they are known to be of the incomplete kind. The quiet chrysalis condition is not observed, and the larvae are born from the egg greatly resembling the adults. The absence of wings is the great distinction between the larval and the imago state, as it is in the closely-allied order of the Orthoptera. The larva moults several times, and the wings are gradually added, the colour of the insect altering also (Fig. 382).

402

VIII.

NEUROPTERA.

THE Neuroptera—the type of which order are the Libellulæ, or Dragon Flies—have four membranous wings, generally rather broad, provided with transverse delicately reticulated nervures, which gives them the appearance of lace. Although one of the least extensive, this Order presents the greatest modifications of form and of habits.

One section of Neuroptera contains some insects which undergo incomplete metamorphoses. The Libellulæ, the Ephemeræ, and the Termites, belong to this category. The insects belonging to the other section, in which are classed the Phryganidæ,* or Caddis Flies, the Panorpatæ, and the Myrmelionides, or Ant Lions, undergo complete metamorphoses. The pupæ of the first walk and live absolutely in the same way as the larvæ; only, at the moment of the last transformation, the skin of the pupa splits, and the perfect insect comes forth. In the case of the second, on the contrary, the pupa is motionless, inactive, and takes no food, as in the Hymenoptera, Coleoptera, &c. In spite of this diversity in their mode of development, all these insects resemble each other too much for us to divide the Order; from which it follows that we must not attach too much importance to differences of transformation by which the insect arrives at its perfect state.

The most interesting insects among the Neuroptera are the Termites, improperly called White Ants, on account of the great analogy which exists between their habits and those of ants. They constitute, by their way of living, a striking anomaly in the order in which their conformation places them. In fact, they live in very numerous societies, and build very solid and very extensive dwelling-places—quite Cyclopean or Titanic works in comparison to the tiny dimensions and weak and feeble appearance of the insect. (PLATE IX.)

• These were separated from the Neuroptera and made a separate order, under the name of Trichoptera, by Kirby.—ED.

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M^m

Many travellers have spoken of these insects. They are met with in the savannahs of North America, in Guiana, in Africa, in New Holland, and even in Europe, whither they have been !imported. M. de Prefontaine relates that, when he was travelling in iGuiana, he saw the negroes besieging certain strange buildings, which he calls ant-hills. They dared not attack them, except from a distance, and with fire-arms, although they had taken the precaution of digging all round them a little fosse filled with water, in which the besieged would be drowned if they made a sortie. These were the termites' nests. Perhaps it is to termites Herodotus alludes when he speaks of !ants which inhabit Bactria, and which, larger than a fox, eat a pound

Iof meat a day.* Retired in the sandy deserts, these gigantic insects 'hollow out (says he) subterranean dwellings, and raise mounds of jgolden sand, which the Indians carry away at the peril of their lives. jPliny, who relates the same fables, adds that there were to be seen in jthe Temple of Hercules the horns of these ants. Even in our own Idays some travellers have repeated absurd fables about termites. They have attributed to them a venom which one cannot breathe liwithout being poisoned; they have said that a single bite was enough I to cause a mortal fever. The truth, as it is revealed to us by ijconscientious observers, is still stranger than these fictions or errors. \ The termites present curious modifications, on the nature of which naturalists are not agreed. There are, in the first place, the perfect I insects, males and females, which are provided with wings; then j there are the neuters, which are divided into soldiers^ whose duty it is I to defend the nest, and into loorkers, upon whom devolve the I architectural works and household cares. These last are smaller than ! the soldiers. Latreille and some other naturalists think that these i workers are the larvae of the termites. Smeathman thinks that the soldiers are the pupae. M. de Quatrefages admits that the soldiers are the neuters, and that the workers are recruited both from the larvae and from the pupae. It may be admitted, with other naturalists, that the soldiers and the workers are neuters: the first, abortive males; the second, abortive females. Here is, indeed, what M. Lespes has observed in the termites of the Landes. Among these insects, the most numerous are the workers: their size is that of a large ant, and their duties are to excavate galleries, to search for provisions, and to take care of the eggs, the larvae, and the pupas.

• De (Quatrefages, "Souvenirs d'uu Xaturaliste," tome ii., p. 377. In iBmo. Paris, i8t;4.

The workers have a rounded head and short mandibles, and are blind. The soldiers, less numerous, have an enormous head — nearly as big as the rest of their body — very strong, crossed mandibles, and are blind like the workers. Anatomy showed M. Lespes that both are neuters — that is, the soldiers, males, and the workers, females — with aborted organs. The larvae of the females much resemble the workers. Those which are to become males or females are distinguished from those which are to become neuters by very slight rudiments of wings, and their pupae show already imperfect wings, hidden in cases; furthermore, they have eyes hidden under the skin. The males and females alone have eyes; they also have wings, which they lose immediately after the coupling. Those which proceed from the pupae with long wing-cases become small kings and queens after their swarming, which takes place at the end of May. The pupae with short wing-cases become perfect in the month of August, and produce larger males and females, which become kings and queens. AH these couples are collected by the neuters; and the queens, large and small, set to work immediately to lay. The largest are much the more fruitful. The workers do not seem to take any care of them at all. With the exception of this last peculiarity, everything probably goes on in the same manner with the exotic termites; but with the latter the queen is an object of worship.

Fig. 383 represents the four types of the republic of the Term, luciftigus. On the left is a worker, on the right a soldier, in tlic centre a winged male, all three very much magnified, the lines drawn by their side showing the natural size. Below the male is the preL nant (jueen (odd d), of a species of which we are about to speak. of the natural size. Many species of termites were studied with care by the English traveller, Smeathman, at the end of the last century, in Southern Africa. His account of them is the most exact and most complete which we have of these insects.* The largest of the species observed is the Termes bellicosus. The workers are a fifth of an inch long, the body soft, and of an extreme delicacy, but the sharp mandibles capable of attacking the hardest bodies. The soldiers are twice as long, and weigh as much as fifteen workers, and may be distinguished by their enormous horned head, armed with sharp pincers. The male weighs as much as thirty workers, and attains to a length of nearly four-fifths of an inch.