j 88 A BOOK OF INSECTS 



be seen clinging in enormous numbers to ponies and 

 cattle. Curiously enough, its bite appears not to cause 

 pain, and beasts which have been bred in the Forest 

 show no signs of annoyance, although strange horses are 

 often driven almost frantic by the irritation caused by the 

 insects crawling over them. All the Hippoboscidce 

 (including the wingless " sheep - tick " or " ked ") are 

 viviparous, the females producing at each birth a full- 

 grown larva which immediately changes to the pupal 

 state. The fleas (Siphonaptera), which are nearly related 

 to two-winged flies, are parasites when adult, but their 

 larvae live an independent life and feed upon the organic 

 matter contained in dust. Perhaps the most completely 

 parasitic of all insects is the female Stylops, an outline of 

 whose life-history has already been given (page 83). 



Carrion-feeding and scavenger insects are most 

 numerous among the two great orders Coleoptera and 

 Diptera. Enormous numbers of flies habitually resort 

 to filth, or to decaying animal matter, both to feed and to 

 lay their eggs ; and their larvae do good service by rapidly 

 consuming these malodorous substances. No less than 

 10,282 maggots of the house-fly have been obtained from 

 fifteen pounds weight of manure after only four days 

 exposure, while it is often asserted that a dead horse 

 would be as quickly demolished by the progeny of three 

 flesh-flies as by a lion. The most interesting scavenger 

 insects, however, are found among the beetles. In the 

 course of a summer ramble, one not infrequently comes 

 across a dead animal, such as a bird or a mouse. If 

 the body be turned over with a stick, some of our native 

 sexton or burying beetles (Necrophorus) may usually 

 be found busily engaged. Both sexes labour, while 

 several pairs often work in company. They scoop away 

 the soil beneath the carcass, and if it be not too large, 



