432 



THE BIOLOGY OF INSECTS 



whence the minute active sporozooites escape into the 

 insect's body-cavity and enter the salivary glands, so that 

 they can be injected into the blood-stream of some other 

 human victim of the mosquito's bite. There is, however, a 

 constant and noteworthy difference in the culicid hosts of 



Fig. 87. — a, Culicme Mosquito and c, Anopheline (females) in resting 

 position ; b, larva of Culex and d of Anopheles showing suspension from 

 surface film. X 8. After L. O. Howard (U.S. Dept. Agr. Ent. Bull. 25). 



the Plasmodia affecting respectively man and bird-hosts. 

 In the case of the latter the insect is an ordinary female gnat 

 of the culicine section of the family, distinguished by 

 the palps being very m.uch shorter than the sucking and 

 piercing proboscis (Fig. 87, a). After R. Ross (1900) had 

 demonstrated the part played by the species of Culex in 



