CULICINES 253 



above list. He does not recognize the subdivision of 

 the anophelines into subgenera, but groups them all 

 under A nophdes. Culicines may also be carriers of protozoal 

 diseases. It was in Culex fatigans that Ross first demon- 

 strated the complete life-cycle of Proteosoma, a bird 

 parasite very similar to the human malaria parasites. 



THE DISTINCTION OF CULICINES INTO GROUPS. 



Theobald considers that the character of the scales on 

 the veins of the wings, head and scutellum are of "great 

 importance. These differ from those in anophelines and 

 in different culicines so markedly that Theobald bases 

 his division into sub-genera on the character of the 

 scales. Yellow fever has been proved to be carried by 

 a culicine belonging to the subdivision Stegomyia. 



In the group " Stegomyia," in addition to the upright 

 fork scales on the head, there are also curved tile- 

 like scales and similar tile-like scales on the scutellum. 

 They are small mosquitoes and usually black with brilliant 

 silver-white markings. These markings, especially those 

 on the thorax, serve to distinguish the different species, 

 and in S. fasciata there is a faint central, narrow silver 

 line on the dorsum, and on each side of this a more 

 conspicuous curved line. 



The S. fasciata (S. calopus) is commonly known as the 

 " tiger mosquito," because of the brilliant striping of the 

 legs and abdomen. 



The breeding-places and habits of the Stegomyia in 

 general, and of S. fasciata in particular, differ greatly 

 from those of the Anophelines, and the prophylactic 

 measures must be varied accordingly. Stegomyia eggs 

 are laid singly, and have no lateral air-floats. They are 

 covered with a thick shell. They float for a time on the 

 surface of the water, but ultimately sink and lie at the 

 bottom of the water in which they were deposited. These 

 eggs are not killed by immersion in water, nor are they 

 destroyed by prolonged desiccation. 



This extraordinary vitality of the eggs is the cause of 



