DECEMBER. 267 



Numerous insects find their food in animal matter ; the 

 Ichneumonidce, as described elsewhere, select almost exclu- 

 sively the caterpillars oiLepidoptera as food for their young, 

 thus preventing their two great increase. The parasitic 

 insects infest birds and Mammalia ; the genus Pulex (the 

 Flea) lives principally on the latter ; the Hippobosca equina 

 on the horse ; and the (Estridce^ in their larva state, on 

 different quadrupeds, such as the ox and deer. But if 

 many animals are annoyed by being made the food and 

 habitation of insects, and even man suffers, both in his 

 person, food, and clothing, by their attacks, how much is 

 nature in general benefited by their unremitting labours in 

 destroying noisome and decayed substances, and lessening 

 the two great redundancy of both animal and vegetable life. 

 There are also many more obvious uses : to the smaller 

 animals, and numerous birds, they present an acceptable 

 food ; many birds feed exclusively on them, and the majority 

 of bats, the shrew, the hedgehog, and the mole prefer them 

 to other nourishment. 



The advantages derived by man from the insect world 

 are very numerous ; many have been already named, and 

 we are also indebted to it for some portion of our food and 

 clothing. The Cossus of the Greeks and Romans was the 



