Diptera 



255 



heads and with bundles of hairs on the body-segments; 

 they live in dust (fig. 143). The pupa is free and 

 shows great likeness to the adult (fig. 143 i^); it is 

 enclosed in a light cocoon of spun silk and dust. 

 The adult Fleas suck blood from birds and mammals. 

 They may be divided into two families (149). 



Pulicidae. — The Puliclda comprise the best known fleas. There 

 are from three to five segments in the palps of the second maxilla ; 

 the head is relatively small ; and the hind-body is elongate and does 

 not become greatly swollen in the pregnant female. The Common 

 Flea (Fukx irritans) (fig. 142 c) it is a too well-known example of this 

 f a m il y, which is 

 world-wide i n i t s 

 range. 



Sarcopsyllidae. 



— The SarcopsyU'td^ 

 or " Jigger-fleas " 

 have large heads 

 and ten-segmented 

 palps to the second 

 maxills. The hind- 

 body is short but 

 becomes immensely 

 swollen in the 

 pregnant female 

 who usually 

 burrows after 

 fertilisation into 

 the skin of her host, 

 causing a painful 

 tumour. The larvs on hatching escape from the host's body. This 

 family is confined to tropical regions (fig. 144). 



Sub-Order B. Orthorrhapha. 



The Orthorrhapha are winged Diptera, the skins 

 of whose pupae (and puparia when present) split open 

 along the back in the manner usual in insects to 

 allow the imago to escape. There is a distinct 

 chitinous head-capsule in the larva. The flies of this 

 sub-order may be divided into two groups accord- 

 ing to the form of the feelers, and the characters 

 of these groups serve to separate the families con- 



FiG. 144. — Hen Y\s:x{,Sarcopsy!iagallinacea),'We?>Vtxn 

 India, etc. Male, magnified ; ant. feelers ; >«. 

 palps, highly magnified. From Packard, Insect 

 Life, vol. 7 (U.S. Dept. Agr.). 



