CATERPILLAR 107 growth is truly astonishing; there is no large animal at all comparable to it for voracity, for some species will eat in 24 hours more than double their own weight ; though less voracious than locusts, they are quite as destructive from their greater fecundity and their wider distri- bution over the vegetable world. According to Count Dandolo, the common silkworm, during the 30 days in which it attains its full size, in- creases in length from 1 to 40 lines and in weight from Y^ to about 95 grains ; during this pe- riod, therefore, it has increased 9,500 times in weight, and has eaten 50,000 times its weight of food. The caterpillar of the privet hawk moth on leaving the egg weighs about -^ of a grain, and at the end of 32 days, when it has acquired its maximum size, it has been known to weigh 142 grains, and to measure over 4 inches in length, thus increasing more than 11,300 times its original weight. According to Lyonnet, the larva of one of the carpenter moths(e0sws ligniperda, Fabr., or genus xyleu- tes of Newman), during the three years in which it is supposed to remain in the cater- pillar state, increases 72,000 times its first weight by a great accumulation of fat for its nutriment in the pupa and perfect states. Most caterpillars feed on vegetable substances, the leaves, flowers, roots, buds, seeds, and even the wood of plants; many domestic pests gnaw woollens and furs, leather, and fatty substances ; while some are quite exclusive in their diet, others are more indiscriminate feeders. When they are very numerous, scarcely any plant escapes their attacks, and at such times their ravages are deplorable, reducing trees in mid- summer to their winter leafless livery. Plants with acrid juices are the favorite food of some species, and the nettle and other spiny shrubs are the natural habitats of many smooth and tender-skinned varieties. Most feed on the exterior of plants, but some of the most destruc- tive and most delicate live in the interior of branches and stems. The sweetest fruits, as pears, plums, and apples, ripen and fall prema- turely, the abodes of caterpillars ; plums are especially liable to be thus inhabited, while the peach and apricot are free from all larvse ; it has been observed that a single fruit rarely contains more than a single caterpillar, the second inhabi- tant, if there be one, being the larva of some other order of insects. Wheat, rye, barley, and other grains are infested by small caterpillars, which gnaw away the whole interior without any external perceptible trace, so that an appa- rently sound heap may be only a collection of useless skins ; a single grain contains just the quantity of provision necessary for the trans- formation of the insect. Another example of the instinct of the lepidoptera is seen in the fact of their depositing their eggs on the parts of the plant which will furnish an easily accessible sup- ply of food to the caterpillar when it is hatched ; their eggs are found glued to fruits, and to flow- ers that are to produce fruits, between the very petals, so that the young find themselves sur- rounded by an immediate supply. Caterpillars are remarkable for the eagerness with which some species will feed upon their fellows, in preference to vegetable substances in profusion around them. Different species select different times of day for feeding ; some eat at all hours, some in the morning and evening, and others only at night ; a knowledge of these habits is of great advantage for the easy destruction of many pests of the vegetable garden. Though generally disgusting objects, the contrast and brilliancy of the colors in some of them are em- inently beautiful. Some species herd together in great numbers, constructing their silken habitations in common ; others live solitary, exposed to light and air, or protected in rolled leaves or silken sheaths ; others burrow in the ground, or conceal themselves in the stems of plants and the pulpy substance of leaves. The caterpillars which live in one nest all come from the eggs of a single insect, and are gene- rally hatched on the same day ; from 200 to 700 may thus be found together, and may remain so through the chrysalis condition, or may sep- Processionary Caterpillars. arate at different periods of life; some, though living in great numbers on the same tree, are solitary with respect to each other, performing no work in common ; the most solitary are the leaf-rollers, which are also the most re- markable for their vivacity. For the mecha- nism of the various abodes of caterpillars the reader is referred to the works of R6aumur, Latreille, Kirby and Spence, and other practi- cal entomologists. The attitudes assumed by caterpillars when attempts are made to catch them are characteristic of species in many cases; some roll themselves into a ring and remain as if dead, the hairy ones resembling little hedgehogs ; others fall instantly to the ground and try to escape by rapid flight ; some attempt to defend themselves by various motions of their bodies. The mode of marching adopted by the " processionary caterpillars" is very remarkable ; these live in society, and when they quit their nest they go in a regular proces- sion, a single caterpillar first and the others in
