INSECTS. 



knots or ganglions, from each of which 

 small nerves proceed to different parts 

 of the body. Whether insects be en- 

 dowed with any senses different from 

 those of the superior animals cannot ea- 

 sily be ascertained. It appears pretty 

 evident that they possess vision, hearing 1 , 

 smell, and touch ; as to the sense of taste, 

 we are left to conjecture, for we are ac- 

 quainted with no facts, by which we can 

 prove that insects do or do not enjoy the 

 sense of taste. The eyes of insects are 

 of two kinds ; the one compound, com- 

 posed of lenses, large, and only two in 

 number ; the other are small, smooth, 

 and vary in number, from two to eight. 

 The small lenses, which form the com- 

 pound eyes, are very numerous ; they 

 amount, in some insects, to many hun- 

 dreds. .The far greater number of insects 

 have only two eyes, but some have three, 

 as the scolopendra; some four, as gyrinus; 

 some six, as scorpions ; some eight, as 

 spiders. The eyes of insects are com- 

 monly immoveable ; crabs, however, have 

 the power of moving their eyes. That 

 insects are endowed with the sense of 

 hearing can no longer be disputed, since 

 frog-hoppers, crickets, &c. furnish us with 

 undeniable proofs of the fact. Nature 

 has provided the males of these insects 

 with the means of calling their females, 

 by an instrument fitted to produce a 

 sound which is heard by the latter. The 

 male and female death-watch give notice 

 of each other's presence, by repeatedly 

 striking with their mandibles against old 

 wood, &c. their favourite haunts. Their 

 ears have been discovered to be placed 

 at the root of their antennae, and can be 

 distinctly seen in some of the larger kinds, 

 as the lobster. That insects enjoy the 

 faculty of smelling is very evident ; it is 

 the most perfect of all their senses. 

 Beetles, of various sorts, the different spe- 

 cies of dermestes, flies, &c. perceive at a 

 considerable distance the smell of ordure 

 and dead bodies, and resort in swarms to 

 the situations in which they occur, either 

 for the purpose of procuring food, or lay- 

 ing their eggs. Insects feed on a great 

 variety of substances; there arefewthings 

 either in the vegetable or animal king- 

 doms which are not consumed by some of 

 them. The leaves, flowers, fruit, and 

 even the ligneous parts of vegetables, af- 

 ford nourishment to a very numerous 

 class; animal bodies, both dead and alive, 

 even man himself, is preyed on by many 

 of them : several species of the louse, of 

 the acarus, of the gnat, and the common 

 flea, draw their nourishment from the sur- 

 face of his body; the pulex ulcerans pe- 



netrates the cuticle, and even enters his 

 flesh. A species of gadfly, oestrus hominis, 

 deposits its eggs under his skin, where 

 the larvae feed. Other caterpillars insin- 

 uate themselves into different cavities of 

 his body. All the inferior animals have 

 their peculiar parasitical insects, which 

 feed on them during their life. There 

 are some insects which can feed only on 

 one species. Many caterpillars, both of 

 moths and butterflies, feed on the leaves 

 of some particular vegetable, and would 

 die, could they not obtain this. There 

 are others which can make use of two or 

 three kinds of vegetables, but which never 

 attain full perfection, except when they 

 are fed on one particular kind ; for ex- 

 ample, the common silk-worm, which eats 

 readily all the species of mulberry, and 

 even common lettuce, neither attains so 

 great a size, nor produces so much silk, 

 as when fed on the white mulberry. 

 There are a great many which feed indis- 

 criminately on a variety of vegetables. 

 Almost all herbivorous insects eat a great 

 deal, and very frequently ; and IT ost of 

 them perish, if deprived of food but for a 

 short time. Carnivorous insects can live 

 a long while without food, as the carabus, 

 ditiscus, &c. As many insects cannot trans- 

 port themselves easily in quest of food, to 

 places at a distance from one another, na- 

 ture has furnished the perfect insects of 

 many species with an instinct, which leads 

 them to deposit their eggs in situations 

 where the larvae, as soon as hatched, may 

 find that kind of food which is best adapt, 

 ed to their nature. Most of the butter- 

 flies, though they flutter about, and col- 

 lect the nectareous juice of a variety of 

 flowers, as food for themselves, always de- 

 posit their eggs on or near to those vege- 

 tables destined by nature to become the 

 food of their larvae. The various species 

 of ichneumon deposit their eggs in the 

 bodies of those insects on which their lar- 

 vae feed. See ICHNEUMON. The sirex and 

 sphex are likewise careful to deposit their 

 eggs in situations where their larvae, when 

 hatched, may find subsistence. The sphex 

 figulus deposits its eggs on the bodies of 

 spiders which it has killed, and encloses 

 it in a cell composed of clay. Some in- 

 sects, at different periods of their exist- 

 ence, makes use of aliment of very differ- 

 ent properties ; the larvae of some are car- 

 nivorous, while the perfect insect feeds 

 on the nectareous juice of flowers : e. sf. 

 sirex, ichneumon, &c. The larvae of most 

 of the lepidopterous insects feed on the 

 leaves and young shoots of vegetables, 

 while the perfect insects either take no 

 food at all, or subsist on the sweet juice 



