FOOD OF INSECTS. 55 



An equal variety in the food of those insects which live on animal 

 matter may also be pointed out. Some live as parasites on the skins 

 of other animals, not excepting even insects themselves, suck their 

 blood, and are a burdensome torment to the animals: to these belong 

 the different sorts of lice (bird and sheep lice), ticks, and mites. 

 Others attack man and the larger animals for only a short time, and 

 draw blood gnats, midges, autumn- flies, breeze-flies, bugs, and fleas. 

 Some breeze-flies (CEstridae) penetrate through the skin into the flesh 

 of the red deer and horned cattle, others live in the stomachs of horses 

 and asses, and one sort in the frontal sinus of sheep. The Ichneu- 

 nionidae feed on the flesh of the larvae of other insects, and often greatly 

 contribute to the extirpation of noxious insects. 



The Carabidae and other carnivorous beetles devour their prey en- 

 tire, immediately after killing it ; while the Cimices and Hemerobii 

 only suck out the juices. The larvse of the stinging-gnat and other 

 flies which live in water devour whole swarms of infusoria alone. A 

 great number live on carrion and the excrements of animals, and thus 

 diminish and destroy the corruption proceeding from such matter : to 

 these belong chiefly the blue-bottle fly, horse-beetle, carcase-beetle, 

 and dung-beetle. Many feed upon prepared animal matter, and become 

 very prejudicial to household economy. Many moths live entirely 

 on hair, leather, wool, and feathers. 



With the various transformations of insects their economy is 

 changed, and consequently their abode is also varied : the caterpillar 

 requires very different food from the butterfly ; the maggot, from the 

 beetle and fly. The larva of Sirex gigas feeds on wood, while the 

 perfect insect preys on flies. The larva of the May-bug or cockchafer 

 lives on roots and tubers ; the beetle, on leaves. 



Many insects are very gluttonous, and often consume more food in 

 a day than is equal to the weight of their bodies. Thus the maggot 

 of the flesh-fly, according to Redi, becomes 200 times heavier in the 

 course of twenty-four hours. Caterpillars digest in one day from one 

 third to one fourth of their weight ; and hence it is apparent that a 

 comparatively small number of caterpillars can entirely strip a tree in 

 a few days. 



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

 state appear to take no nourishment, such as the day-flies (Ephe- 

 meridse), and the breeze-flies (GEstridae) ; 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 Bombycidse, seem to take no nourishment in the perfect 

 state. 



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 

 tjie greater number, live without making any previous supply of food. 

 The larvse of the caterpillar-killing kinds of wasps (Sphegidse), of wild 



