INSECTS 



227 



The remedy is easy to understand. If the ponds or pools 

 of standing water are taken care of, the malarial mosquitoes 

 will not be able to find suitable breeding places. These 

 stagnant waters may be drained away, or covered with crude 

 oil, or fish may be kept in them to feed upon the wrigglers. 

 Barrels and other vessels of water must be emptied or covered 

 with oil. Houses should be screened to keep out mosquitoes. 

 It is believed that the malarial mosquitoes are never active 

 during the day when the sun is shining, 



Fia. 126 



FIG. 125. Malarial mosquito wriggler at left, common at right. (Div. 

 U. S. Dept. Agric.) 



FIG. 126. Malarial mosquito below, common above. (Div. Ent., U. S. Dept. 

 Agric.) 



It is not difficult to distinguish the malarial mosquitoes 

 from the other common forms. The position of the wrigglers 

 in the water when at rest is parallel to the surface of the 

 water, while the resting position of the common mosquito 

 wriggler is nearly perpendicular to the surface of the water 

 (Fig. 125). When the adult malarial mosquito is attacking 

 a person the body is nearly perpendicular to the surface 

 attacked; while with the common mosquito it is nearly level 

 with the surface (Fig. 126). 



Yellow fever is also spread by mosquitoes of a particular 



