MOSQUITOES 307 



The larva, unlike that of Culex or Stegomyia, is depressed, with 

 a small head, and lies on the surface of the water. Its breathing 

 tube is very short, and its food consists of organisms on or near 

 the surface. The species of Anopheles known to be dangerous as 

 a malarial carrier is A. maculipennis Say. Other species may be 

 found to be equally dangerous. 



Control. That oil of citronella applied without dilution to the 

 back of the neck, face, hands, and wrists upon entering infested 

 localities is fairly effective so long as it lasts, is not fanciful, and 

 it is one of the best repellents. Care should be taken not to allow 

 citronella to come in contact with one's eyes. The same substance 

 mixed with vaseline is more lasting in its effect. Windows arci 



Fio. 315. Mosquito larva, showing breathing tube, also egg mass, and single egg, all much 



enlarged. (Lugger.) 



doors and porches of houses should be thoroughly screened in 

 summer; all tanks or rain barrels should be either screened or 

 treated with kerosene oil. Put a thin film on the surface. Tin 

 cans, broken dishes, etc., which hold water should not be allowed 

 to accumulate in rubbish piles or elsewhere. Eavestroughs 

 dammed by leaves and twigs form good breeding places, as do 

 also tracks of stock around drinking troughs or small indentations 

 along the shore of pond or lake, as well as the drain ditches hi the 

 fields where water stands. Standing water in ditches or pools 

 suggests the following methods of treatment. The water may be 

 drained away, or a film of kerosene may be sprayed or allowed 

 to flow over the surface. Depressions may be filled with earth. 

 Small fish may be introduced into ponds, since the latter prey 

 upon immature forms of mosquitoes. Rooms may be freed by 



