FOOD OF INSECTS, 



103 



the leaves, without touching the epidermis (mining caterpillars) ; others only 

 the upper or under surface of the leaves (many leaf-rollers, Tortrices) ; while 

 a fourth division devours the whole substance of the leaf (the larvae of many 

 other Lcpidopterous insects). 



318. Of those which feed on flowers^ there are some which eat the petals 

 (the larvae of iVoctua verhasci, the mullein-moth, N. linariae, &c.) ; others 

 choose the farina in a perfect state (bees, the rose-chafer, Cetdnia, the 

 Lepturidae, &c. &c.) ; and a still greater number the honey from the necta- 

 ries (most perfect Lcpidopterous insects, wasps, and flies). There are also 

 insects which, not satisfied with any existing part of the plants as such, 

 cause injury to one part or another, by occasioning a peculiar body or 

 excrescence in which their young live, as the various sorts of gall insects 

 and other sorts of flies. But insects are not confined to plants alone in their 

 living and unused state. The death-watch, or ticking-beetle (Anobium), 

 feeds on wood which for years has been used in our dwellings, and in various 

 articles of furniture and utensils. 



319. From what has been said it will appear, that a single plant can 

 support a host of various sorts of insects on its different parts ; whence it 

 also appears, that the number of insects greatly exceeds that of plants. 



320. 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 skin of other 

 animals, not excepting even insects themselves, suck their blood, and are a 

 burdensome torment to the animals : to these belong the diff^erent sorts of lice 

 (bird and sheep lice), ticks, and mites. Others attack man and the larger ani- 

 mals only for a short time, and draw blood — gnats, midges, autumn-flies, 

 breeze-flies, bugs, and fleas. Some breeze-flies (CE'stridae) 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 

 /chneumonidae feed on the flesh of the larvae of other insects, and often 

 greatly contribute to the extirpation of noxious insects. 



321. The Carabidae and other carnivorous beetles devour their prey entire, 

 immediately after killing it ; while the Cimices and Hemerobii only suck 

 out the juices. The larvae 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, carcass-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. 



322. With the various transformations of insects theh- economy is also 

 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. 



323. 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. 



