(From in, into, and seco, to cut). An insect. These animals are thus named from their being almost wholly divided in the middle.
We deferred considering this class of animals in a physical or a medicinal view when we treated of the Animal kingdom, q. v., because we had not received the last labours of Cuvier and La Treille. Insects were most strictly distinguished by Lyonnet, who styled them animals without any vertebrae, with articulated paws or limbs. The flesh is soft, but the skin hard, scaly, or crustaceous, to which the muscles are attached; though the true crustaceous animals should be separated from insects, as having a muscular heart, and breathing by means of gills. See Crustacea.
Another distinction of insects is their colourless blood. If some insects are bruised, a red fluid is discharged; but this has, in general, no relation to blood, except when blood has been previously swallowed; and in some insects it is a secreted fluid under the eyes. Yet, from the late observations of Cuvier, red blood seems to occur in some animals of this class.
The arrangement of insects is scarcely the object of this work. We may, however, remark, that they have been considered for this purpose in all their varied relations. Swammerdam has preferred, as the basis of his classification, their metamorphoses; Linnaeus the organs of motion; Fabricius those of nutrition. The system of Linnaeus is certainly the best and most natural; yet later observators have found some inaccuracies in his characters, and less exact distinction, in his apterous insects. De Geer and Olivier have lessened these inconveniences by stricter discriminations, and forming a new order, the orthopterae, taken from the haemipterae. Indeed, we consider Olivier's arrangement as the best and most natural; more simple than La-treilles, more correct than that of Fabricius.
Insects may be considered in a work like the present as articles of food, as medicinal bodies, as either useful or detrimental to mankind. If we except the crustacea, we shall find few species used at any time as aliment. The locust (gryl/us cristatus Linnaei) is used in the east as food. It is said to taste like a pigeon, but more insipid, and is seldom eaten but when other food is scarce. Its price is high only in times of famine. The wings and feet, sometimes the intestines, are separated. The Bedouins of Egypt eat them roasted alive; the Arabians roast and eat them with butter; or, when they wish for a dish of peculiar delicacy, they parboil, and then fry them in butter. The inhabitants of Morocco dry them, and those of Barbary pickle them. Forskal, however, tells us that they have very little flavour, and that they are far from nutritious, and occasion melancholy, or cutaneous affections. In different parts of India and America the larvae of coleopterous insects, bred in the internal parts of trees, as the weevil, a species of lucanus, the passalus of Fabricius, the prionus cervicornis, & c.; but these can only be procured with much trouble, and can never form an article of food. We have heard of the Worms of filberts being eaten as a delicacy, and said to be rich, like marrow, with the taste of the nut, and that the maggots of every fruit have its peculiar flavour. The Romans used to eat the larva of an insect which they styled cossus, supposed to be the same which is found under the bark of the willow or the ash; but this larva, which is a true caterpillar, has an insupportable smell and probably a disagreeable taste; so that it is certainly not the same. In Africa the inhabitants eat the white ants. The galls formed by a cynips on a species of sage in the isle of Crete, and on the glechoma hede-racea Linnaei, are accounted by children a peculiar delicacy. The honey of the bee is too well known as a
5 M 2 nutritious substance, and a medicine to be particularly noticed. The honey of some districts in America is, however, poisonous (see American Transactions); and new honey will often disagree with the bowels, when these are peculiarly tender and irritable.
If, with much trouble, we have collected a scanty catalogue of nutritious insects, we shall not find the materia medica greatly enriched from these minute animals. The cantharides are, however, of considerable importance in medicine (vide in verbo); and the ants are said, by infusion, to furnish a pleasant and salutary acid drink in fevers. (See Formica.) The galls of the oak and the bedaguar of the rose tree, though the effects of insects, derive all their virtues apparently from juices of the tree and vegetable. The carabus, chryso-cephalus, two species of the sphaex of Linnaeus, two of the chrysomela and coccinella, three of the curculio, have been recommended in tooth ach. The insects are to be bruised between the fingers, and the tooth and gums rubbed with the same fingers. The meloe majalis and proscarabaeus are of the nature of cantharides, but less powerful. The oniscus asellus (millepes) was formerly much employed as a stimulating expectorant in dropsy, in obstructions of the liver, in asthma, and cynanche. Its nauseous acrimony points it out as a medicine of importance; but its disgusting appearance has occasioned its neglect. The coccus of the cactus coccinelliferus (cochineal) is said to be stimulant and diuretic; the same insect of the ficus Indica, and quercus ilicis, the lac, and kermes, to be astringent; but modern practice neglects both. We have said that the more refined naturalists had separated the spiders from the insects; but we may mention here, without an apology, the use of the spider's webs in external haemorrhages, which act in assisting the concretion of the blood. We mention it also to add, that an ant found in Cayenne, the formica fungosa of Fabricius, composes its bed of a down so fine, that it generally succeeds in stopping arterial haemorrhages on the same principle. The ancients used the horns of the cervus volans as an absorbent; and Linnaeus tells us, that in Sweden a species of gryllus is irritated so as to bite warts, and that the fluid from its mouth destroys them. The trivial name is assigned from this property.
Among the advantages derived to mankind from insects, we need not name the silk, and the scarlet dye from the cochineal. Many insects, besides that of the mulberry, spin a silken pod; and from many of the cocci, a brilliant colour, though inferior to that of the cochineal, may be obtained. From the silk worm's pod, the Chinese, it is said, prepare a brilliant and durable varnish. This worm affords also the Bengal root, styled in England Indian grass, so useful to the fisherman. We need not add Reaumur's attempt to make silk from spider's webs, in which it has been supposed he would have succeeded, could he have induced them to live peaceably with each other. The gum lac and bees wax are well known, and some naturalists have attributed amber to these animals. Among the advantages of insects to mankind, we may also reckon their furnishing birds with a copious supply of nourishment, and their destruction of putrid matter and of each other.
The chief disadvantages are derived from their destructive ravages on books and furniture, and, above all, from the diseases which they occasion. (See Ani-malcula.) The very troublesome itching produced by many species of acarus is well known. The louse, the flea, the bug, and the mosquito, are the common enemies of our repose; and in warm climates are far more numerous and fatal. The locusts, which destroy our harvest, the insects so fatal to vegetables of every kind, are scarcely objects of our attention at this time. They must be watched in their state of larvae, when they may be at once extirpated. The most destructive flies escape our attention by their harmless or pleasing appearance in this state of disguise.