276 SANITARY ENTOMOLOGY 



Determination of Source of Mosquitoes 



It is of primary importance in planning a mosquito campaign to 

 determine the direction and distance of flight and behavior of mosquitoes 

 in the area to be controlled. Zetek (1913, 1915) has elaborated methods 

 for determining these points. He uses as dyes aqueous solutions of eosin, 

 fuchsin, gentian- violet, bismarck-brown, methylene-blue, and orange-g, 

 mixing one gram of dry stain to 50 c.c. of water. By means of an 

 atomizer a fine spray is allowed to fall upon the mosquitoes. They should 

 not be sprayed directly. Evening hours are best for their release and 

 care must be taken not to carry away individuals on the body of the 

 agent. There should be careful observations of wind, climatic condition, 

 direction of flight of the mosquitoes, and the movement of human beings. 

 To determine the flight window traps, examination of buildings and 

 general sweeping are necessary. The place and hour of collection must 

 always be noted. To detect the dye a testing solution is made of three 

 parts glycerin, three parts alcohol, and one part chloroform and the 

 specimens are individually touched with a camel's-hair brush moistened 

 therein. 



Leveling and Filling Water Holes 



Details of men may be designated to look after the leveling of ground 

 where water is apt to gather and remain, and to fill up small puddles, 

 pools, hoof marks, ruts, etc., which serve no useful purpose and where 

 drainage is inadvisable. Holes in trees should be filled up with cement. 

 Stumps which hold water should be grubbed out and the stump holes 

 filled. In rocky streams pot-holes in the rocks often breed many mos- 

 quitoes. If possible the rock should be grooved, or removed, or the 

 holes may be filled with cement. 



Ditching and Clearing Streams and Swamps 



Other details may be designated to clear stream beds and drain low 

 lands. Spring lands, bogs, and swamps furnish an abundance of mos- 

 quitoes and are the first places to receive the attention of the ditching 

 squads. Ditches must be constructed to carry off" standing water.' These 

 should be laid out by an engineer. The ditches must have straight banks 

 and even bed and must be kept free of vegetation. Sometimes it is neces- 

 sary to spray the vegetation along the ditches with oil, and burn. All 

 borrow-pits and puddles caused by grading roads and railways should 

 be connected up by a ditching system or filled. Flowing streams usually 

 have trees along their sides. Under such trees water is often trapped 

 and forms a quiet, undisturbed place for mosquito larvas. Trees must not 



