56 DISTRIBUTION AND HABITS OF INSECTS. 



bees, and of a few other insects, are provided by their parents with a 

 stock of provisions sufficient for their nourishment in the larva state. 



Distribution and Habits of Insects. 



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 feed a numerous host of them. With respect to their 

 habitation, insects are divided into those which live upon land or 

 water. 



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 ; 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 pupse 

 live in water, but as perfect insects on land, or in the air. 



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 develop- 

 ment. 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 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. 



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

 inside of the body, as the larvae of ox and horse breeze-flies (GEstridae). 

 The two latter leave their first abode before entering the pupa state, 

 which they effect in the earth, and hover as flies round the animals to 

 deposit their eggs iipon them. 



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

 they construct for themselves a house composed of various kinds of 

 vegetable or animal matter ; for example, many caterpillars. A few 

 species live in society, such as bees, ants, wasps, &c. 



By obtaining a general knowledge of the abodes of insects, it is 

 evident that the observer of the economy of insects will be able more 

 satisfactorily to combat many that are injurious to him ; as thus he 

 can, with little trouble, greatly diminish or entirely annihilate those 

 which he has ascertained to live in society, or in places of easy 

 access* 



