104 DISTRIBUTION AND HABITS OF INSECTS. 



324. Opposed to this gluttony of caterpillars, some insects in their perfect 

 state appear to take no nourishment, such as the day-flies (.Ephemeridse), 

 and the breeze-flies ((E'stridae); the latter of which, in their larva state as 

 maggots, feed on the flesh of horned cattle and red deer. Even among the 

 Lepidoptera, many of those which spin cocoons, especially .Bombycidae, seem 

 to take no nourishment in the perfect state. 



325. Many insects only eat in the day, others in the evening, and a third 

 division, such as the caterpillars of the night-moths, only in the night. 

 Most of them seek their own food ; but a few, namely, the larvae of bees, 

 which live in communities, humble bees, wasps, and ants, are fed by the 

 perfect insect. Many stow away their food ; others, indeed the greater 

 number, live without making any previous supply of food. The larvae of 

 the caterpillar-killing kinds of wasps (^phegidae), of wild bees, and of a few 

 other insects, are provided by their parents with a stock of provisions suffi- 

 cient for their nourishment in the larva state. 



Subsect. 4. Distribution and Habits of Insects. 



326. The distribution of insects is in exact proportion to the diffusion of 

 plants ; the richer any country is in plants, the richer it is also in insects. 

 The polar regions, which produce but few plants, have also but few insects ; 

 whereas the luxuriant vegetation of the tropical countries feeds a numerous 

 host of insects. With respect to their habitation, insects are divided into 

 those which live upon land or water. 



327. Those which live in the water either never leave that element, or 

 are able to live at will either in the water or on the earth, at least for a 

 short time j for example, many water -beetles. Many live at certain periods 

 of their development in water : at others, on land ; such as many sorts of 

 flies, and all the dragon-flies, which as larvae and pupae live in water, but as 

 perfect insects on land, or in the air. 



328. Land insects live in the earth, under stones, in decayed wood, in 

 putrid animal substances, &c. Of these some pass their whole lives in 

 these places, others only during a particular period of their development. 

 The larvae of the dung-beetle live deep under the ground, while the perfect 

 insect inhabits the excrement of animals ; many of the larvae of flies live in 

 carrion or excrement, while the perfect insect flies about in the open air. 

 A very great number choose the different parts of plants for their abode, as 

 the roots, bark, inner bark, alburnum, wood, pith, buds, flowers, leaves, and 

 fruit. They change their abode in every new stage of their development. 

 Thus the bark-beetle, which in the larva state lived under the bark, swarms 

 in its perfect state upon the trees ; the curculio of the apple-tree, the larva 

 of which infests the bottom of the apple blossom, crawls on the trees, or on 

 the surrounding ground ; the mining- moth, which as a larva lives under the 

 cuticle of the leaves, flutters in its winged state about the flowers and leaves. 



329. A small number live upon other animals, on the skin, such as lice, or 

 in the inside of the body, as the ox and horse breeze-flies (ffi'stridae). The 

 two latter leave their first abode before entering the pnpa state, which they 

 effect in the earth, and hover as flies round the animals to deposit their eggs 

 upon them. 



330. Most insects live solitarily, either without any definite dwelling, or 

 they construct for themselves a house composed of various kinds of vegetable 



