HOUSEHOLD AND CAMP INSECTS 31 



The most effective measures for the prevention of mosquito 

 breeding are the draining or filling of all such areas, the elimination 

 of useless water containers, and the adequate care of others. The 

 drained or filled areas are permanently eliminated as breeding 

 places. The use of kerosene or a moderately heavy crude petroleum 

 distillate is a very effective method of destroying mosquito larvae, 

 since with few exceptions they must come to the surface in order 

 to obtain air, and the film of oil, if maintained, means the speedy 

 destruction of the larvae. It is even possible to use oil on cisterns 

 providing the water for domestic use is drawn from below the sur- 

 face, or any such containers can be protected by mosquito-proof 

 coverings, either wooden with a screened ventilator, or a tight 

 screen. The essential is to prevent ingress or egress of the insects. 

 The systematic sterilization by heat of old tin cans and then batter- 

 ing them so as to prevent their holding water, is an excellent 

 practice, for the control of flies as well as mosquitoes. 



A very efficient larvicide has been developed by the Isthmian 

 Canal Commission. 66 It is prepared as follows : 



" One hundred and fifty gallons of carbolic acid is heated in a 

 tank to a temperature of 212 F. ; then 150 pounds of powdered or 

 finely broken resin is poured in. The mixture is kept at a tem- 

 perature of 212 F. ; 30 pounds of caustic soda is then added and 

 the solution kept at 212 F. until a perfectly dark emulsion without 

 sediment is obtained. The mixture is thoroughly stirred from the 

 time the resin is used until the end. 



" The resultant emulsion makes a very good disinfectant or 

 larvicide. In fact, i part of it to 10,000 parts of water will kill 

 Anopheles larvae in less than one-half of an hour, and I part to 

 5000 parts of water will kill Anopheles larvae in 5 to 10 minutes or 

 less.'' This was prepared in 1909 at a cost of $.1416 a gallon, and 

 has demonstrated its utility under exacting tropical conditions. 



Flake naphthalene scattered upon the surface of water at the 

 rate of I gram to 462 square centimeters of surface killed mos- 

 quito larvae in 24 hours, and the author is of the opinion that the 

 same effect may be obtained by suspending the naphthalene over the 

 water and thus avoid tainting it, something very desirable for 

 cisterns and wells. 67 



A mosquito trap has been designed to fit an opening in a tent or 

 building. It consists essentially of a rectangular frame carrying a 



66 Howard, Dyar & Knab. The Mosquitoes of North and Central America 

 and the West Indies, i :38.s-86. igi2. 



67 Bacot. Brit. Med. Jour., July 4, 1914, p. 15. 



