INSECTS IN GENERAL. 67 



well the substances where the latter will find proper nourish- 

 ment, and deposit their eggs accordingly. Thus the lepi- 

 doptera, which live usually on the honey which they extract 

 from flowers, never fail to lay their eggs on or near the plants 

 which are fitted for the support of their caterpillars. The 

 gnats are, in effect at least, perfectly well aware that their 

 larvae must live and be nourished in the water, and there- 

 fore they place their eggs upon its surface. It is the same 

 with many other insects, as the ephemera, libellulinae, &c. 



Among the insects which live in a social state there are 

 some, which (as the bees) are obliged to choose a dwelling 

 mutually to assist each other in procuring the necessary food, 

 and to accumulate a certain quantity of it to serve as provi- 

 sion for the winter. Others, like the ants, unite and labour 

 in common to seek food, not so much for themselves as for 

 their larvae, which are incapable of providing for them- 

 selves. 



Many insects can subsist only on one species of food, and 

 never vary in their taste. Such are a great number of cater- 

 pillars, which live on certain leaves, without being able to 

 touch any others. They die immediately if a supply of these 

 leaves should be wanting. 



There are insects which eat often, and have need of almost 

 perpetual nutriment. They cannot fast for any length of 

 time without serious injury. These are the herbaceous 

 tribes. Others can remain a long while without taking food, 

 which is the case with carnassial insects, and such as subsist 

 on living prey. This is a remarkable analogy between the 

 present and the preceding classes. 



Some insects live on the leaves of trees. This is the case 

 with the larvae of almost all the lepidoptera, and with those 

 of many coleoptera, hymenoptera, &c. Others subsist only 

 on the juice of the leaves and the stalks, as the cigalce, the 



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