Diptera 



253 



of the higher Lepidoptera. It is rarely enclosed in a 

 cocoon but lies buried in the ground, floats in the 

 water, or is protected by the last larval skin which, 

 separating from the pupa-skin, remains around it as 

 a hard case {puparium) (fig. 1406-). Flies and their 

 larvae live in the most diverse manner. Some flies 

 attack back-boned animals and suck their blood, 

 some prey on smaller insects, some suck honey, and 

 some find their food in decaying animal and vegetable 

 matter. A large number of dipterous larvae eat refuse 

 or carrion, many feed 

 inside growing vege- 

 table tissues, and 

 some prey or are 

 parasitic on other 

 insects (4, 151). 



Classification. — 

 The Diptera pro- 

 bably outnumber any 

 of the other orders 

 in individuals and 

 species, including 

 many families, which 

 were formerly 



rrronnpH in two Hivi- Fig. 142.-3. pupa of House-fly (yif«JC3 domes- 

 grOUpea m CWO UlVl ^.^^^^ magnified 10 times ; b. tail-end of young 



sionS founded mainly larva, more highly magnified. FromHoward, 



. r r \ Bull. 4 (n.s.), Div. Ent. U.S. Dept. Agr. 



on the rorm or the 



feelers (150). The nature of the larva and the way 

 in which the pupa-skin splits open are now con- 

 sidered of greater importance, and the Diptera are 

 often divided into two sub-orders founded on this 

 character (149, I5I> 153)- T^^ Fleas are however 

 such a very aberrant parasitic group of Diptera that 

 they seem fully entitled to rank as a third sub-order. 

 Indeed by some writers (95, 97) they are reckoned as a 

 distinct order (Aphaniptera or Siphonaptera). 



