ENTOMOLOGY

276 SANITARY ENTOMOLOGYDetermination of Source of MosquitoesIt is of primary impo~ance in planning 0. mosquito campaign todetermine the direction and distance of flight and behavior of mosquitoesin the area to be controlled. Zetek (1918, 1915) has elaborated methodsfor 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 anatomizer 0. fine spray is allowed to fall upon the mosquitoes. They shouldnot be sprayed directly. ,Evening hours are best for their release andcare must be taken not to carry away individuals on the body of theagent. 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 andgeneral sweeping are necessary. The place and hour of collection mustalways be noted. To detect the dye a testing solution is made of threeparts glycerin, three parts alcohol, and one part chloroform and thespecimens are individually touched with a camel's-hair brush moistened!herein.Leveling and Filling Water HolesDetails of men may be designated to look after the leveling of groundwhere water is apt to gather and remain, and to fill up small puddles,pools, hoof marks, ruts, etc., which serve no useful purpose and wheredrainage is inadvisable. Holes in trees should be filled up with cement.Stumps which hold water should be grubbed out and the stump holesfilled. In rocky streams pot-holes in the rocks often breed many mosquitoes.If possible the rock should be grooved, or removed, or theholes may be filled with cement.Ditchilng and Clearing Streams and SwampsOther details may be designated to clear stream beds and drain lmvlands. Spring lands, bogs, and swamps furnish an 'abundance of mosquitoesand are the first places to receive the attention of the ditchingsquads. Ditches must be constructed to carry off standing water. Theseshould be laid out by an engineer. The ditches must have straight banksand even bed and must be kept free of vegetation. Sometimes it is necessaryto spray the vegetation along the ditches with oil, and burn. Allborrow-pits and puddles caused by grading roads and railways shouldbe connected up by a ditching system or filled. Flowing streams usuallyhave trees along their sides. Under such trees water is often trappedand forms a quiet, undisturbed place for lJlosquito larvre. Trees must not