210 DISEASES DUE TO PROTOZOA 



and development in regard to infectivity, except that 

 they require d'ffering times for their full development. 

 The female mosquitoes of the genus Anopheles carry 

 the disease from one person to another. They fly and 

 bite in the early evening. These mosquitoes may be 

 recognized by their position on a surface. Their 



FIG. 64 



Egg of Culex (a) laid together in "small boat;" those of Anopheles (6) 

 separate and rounded. (From Kolle and Hetsch.) 



FIG. 65 



a b 



Larva of Culex (a) hangs nearly at right angles to water surface; those of 

 Anopheles (6) are parallel to the surface. (From Kolle and Hetsch.) 



body forms a large angle with the surface, and the head 

 is on a line with the body. The ordinary mosquito, 

 Culex, stands parallel with the surface with the head 

 bent down. Furthermore, the wings of the Anopheles 

 are furred on the flat surface, while the Culex wings 

 are only fitted with widely set, fine hairs on the edges. 

 There are many other differences, but these will 



