OETHOPTEEA. 237 



the most part, Beetles feed on decaying substances 

 such as dung, &c., and are therefore useful creatures ; 

 there are between 40,000 and 50,000 species of them. 

 Beetles have been called the scavengers of nature, and 

 truly they are so, for they (with other insects) clear oft* 

 all dead matter, whether animal or vegetable; the 

 Geotrupes stercorarius, and others, dig holes in the 

 ground and bury the excrement which is deposited on 

 the surface, thus doing a great service to vegetation, 

 taking it down to nourish the roots of the grass and 

 other plants instead of allowing it to harden and 

 decompose on the surface. All dead animals are at once 

 attacked and devoured by insects, and the Beetles play 

 their full share in this necessary operation. 



There are certain Beetles, called Burying Beetles 

 (Necrophorus vespillo), which remove the earth from 

 under the dead bodies of small animals, such as birds or 

 mice, till they are beneath the level of the ground, 

 when they cover them up and deposit their eggs in 

 them ; these bodies form stores of food for the future 

 larvae. 



The Stag Beetle (Lucanus cervus, fig. 22), the Dor 

 Beetle (Geotrupes stercorarius), the Cockchaffer (Melo- 

 lontha vulgaris), the Musk Beetle (Cerambyx mos- 

 chatus, fig. 16), and the Lady -bird (Coccinella), are well- 

 known members of this order. 



2. OETHOPTERA (Straight- winged). 



The Orthoptera are those insects whose wings fold longi- 

 tudinally ; they have two pairs, but the anterior pair are 

 horny and serve as wing-cases to the posterior pair ; their 

 food is chiefly vegetable, but to many of their species 

 any kind is acceptable, as their mouths are suitable for 

 grinding-up hard substances. The Locusts (Locustida?, 

 fig. 21), Grasshoppers (Gryllidae), Crickets (Achetid^, 

 fig. 16), and Cockroaches (Blattidae), or Black-beetles, 

 as they are sometimes incorrectly called, belong to this 

 tribe. Their metamorphoses are not so complete as in 

 many other insects, for they never entirely change their 



