PUBLIC HEALTH 11 



are occasionally to be found in the growth along the sides 

 of slowly flowing streams. The breeding grounds of A. cru- 

 cians are mainly restricted to regions adjoining the salt and 

 brackish marshes along the coast, although the larvae are 

 most abundant in fresh water. The two Anopheles occurring 

 on the Pacific coast region, A. pseudopunctipennis and A. 

 occidentalis, have habits similar to those of quadrimaculatus, 



FIG. 3. Anopheles punctipennis, female. 



although the second species breeds in brackish waters also. 

 As is the general habit among adults of Anopheles, these 

 mosquitoes feed mainly at twilight and malaria is acquired 

 only by persons who expose themselves to their bites after 

 nightfall. Occasionally they bite during the daytime, but as 

 malaria appears never to follow such bites it seems probable 

 that only newly emerged females and consequently non-in- 

 fected ones bite at this time, as is the case with the yellow- 

 fever mosquito. 



