DIPTEKA 



48 



sands of the germs, 

 Hcemameba terti- 

 ana, are taken into 

 its stomach, from 

 which they migrate 

 to the salivary 

 glands (Fig. 18), and 

 thence are forced 

 with the saliva into 

 persons bitten later. 

 The saliva is ejected 

 by the mosquito 

 to break up the red 

 blood cells which 

 are too large to pass 

 through its pro- 

 boscis. The itch- 

 ing and painful 

 effect of the bite are 

 due to the poison 

 injected along with 

 the saliva. 



Lately it has been shown that yellow fever is trans- 

 mitted by mosquitoes and in no other way. The only 

 offender is Stegomyia fasciata. It is probable that these 

 insects are responsible for some other diseases affecting 

 man. 



Destruction of Mosquitoes. On account of the fact that 

 the mosquitoes are responsible for more sickness and 

 death annually than all the wars of the world, efforts are 

 being made to exterminate them by draining the stagnant 



FIG. 19. Photograph of heads of mosquitoes. A, 

 male ; -B, female ; a, antenna ; pi, palpus ; pr, 

 proboscis. 



