DIPTEEA OR TRUE FLIES. 



257 



apterous Diptera which are perhaps more neai'ly related to the 

 Fungus Gnats [M ijcetopMlidce) than to any other Diptera. 

 PulicidsB have a sucking and piercing mouth by which they 

 draw out the blood of their hosts. The body of the flea is 

 flattened from side to side, and the legs are well developed to 

 enable them to perform their hopping movements. Some have 

 compound eyes {TricTiopsylla (/allince and Pulex irritani), others 

 have none {Hystrichopsylla talpce, the Mole Flea). The eggs or 

 " nits " are laid in dust and dirt, and the larvfe are pearly- white 

 fourteen-segmented grubs, with a large brown head, and pupate 

 where they live, as small brown chrysalids. Some feed on 

 scurf, hairs, feathers, and other epidermal productions. Many 

 of the species can be easily identified by the number of spines 

 in the curious comb-like structure on the prothorax. 



The Hen-flea (Tbichopstlla GALLiNiE). 



The Hen-flea is often very troublesome in fowl-roosts. It is 

 a species common to several birds, and is dark-brown in colour. 

 We find them most abun- 

 dantly in dirty fowl-nests, 

 especially where the houses 

 are damp and badly ven- 

 tilated and lighted. Hen- 

 fleas live in the nests, where 

 in the corners and crevices 

 the nits are deposited ; the 

 larvae and pupae are found 

 amongst the straw, feathers, and dung in the nests. The fleas 

 feed off the birds at night, sucking their blood, and produce 

 great irritation. These insects are very injurious to setting hens, 

 and often cause them to neglect their eggs. The small white 

 maggots have a curious little prooesSj the " post-frontelle," on 

 their head, on coming from the egg, by which they force their 



R 



Fig. 147. — Larva and Pupa of Hen-flea 

 (Trichopsylla gallince). 



