DIPTERA. 



269 



lected from dogs, hens, pigeons, and birds. The fleas 

 are semi-parasitic in habit, the adult hving among the 

 hairs of mammals and the feathers of birds, and suck- 

 ing the blood of these animals. The larval and pupal 

 stages are passed, however, in the dirt and refuse on 

 the ground. The adults present interesting modifica- 

 tions of structure,, as they are well adapted for the life 

 they live (see Fig. 218, which represents one species 



Fig. 218. 



of flea). Their skin is tough and capable of resist- 

 ing pressure. There are no compound eyes, but only 

 two ocelh. The mouth parts (see Fig. 218) are fitted 

 for piercing and sucking the blood of animals. The 

 wings are reduced to mere scales (not clearly shown 

 in Fig. 218) which can be of Httle or no use, and this 

 condition is correlated with the structure of the tho- 

 racic rings, these having lost their complex modifica- 

 tions, and become distinct and similar to the abdomi- 

 nal segments. With the loss of the power of flight, 



