514 THE INVERTEBRATA 



the flea and the faeces deposited on the skin of the host are rubbed 

 into the wound by the scratching which follows the irritation from 

 the bite. 



Ceratophyllus fasciatus, the European rat flea, also transmits the 

 plague organism as also can Pulex irritanSy but since the latter does 

 not live successfully on rats, it is never likely to prove a source of 

 trouble* 



Order STREPSIPTERA 



Small parasitic insects, allied to the Coleoptera, with winged, free- 

 living males and larviform females, which never leave the interior of 

 their host. 



Sty lops causes great modification of its host, the bee (Andrena). 



