THE HOUSE FLY. 



19 



scattered evenly over the surface and then wet down with water. 

 The use of tjiis mixture adds to the manure the important elements, 

 nitrogen and phosphorus. 



Of course there are a number of other insecticides which are effective 

 against fly larva?. Potassium cyanid, Paris green, arsenite of soda, 

 etc., are effective, but they are hardly to be recommended for general 

 use because of their extremely poisonous nature. Others, like 

 pyridine, aniline, and nitrobenzene emulsion, are too expensive 

 when used in amounts sufficient to kill maggots. 



MAGGOT TRAP FOR DESTRUCTION OF FLY LARVJE FROM HORSE MANURE. 



The second method of handling manure is one which does not re- 

 quire the application of chemicals. It is based on the fact, mentioned 

 on page 6, that the larva? of the house fly, when about ready to 

 pupate, show a very strong tendency to migrate, leaving the spot 

 where they have been feeding and crawling about in search of a 

 suitable place for pupation. This migration takes place mostly at 

 night, and the larvae sometimes crawl considerable distances away 

 from the manure pile. Now it is possible by means of a very simple 

 arrangement called a maggot trap to destroy fully 99 per cent of all 

 maggots breeding in a given lot of manure. A successful maggot 

 trap which the Maryland Agricultural College constructed at the 

 college barn is shown in figure 14. The trap was designed by the 



FIG. 14. A maggot trap for house-fly control. View of the maggot trap, showing the concrete basin 

 containing water in which larvae are drowned, and the wooden platform on which manure is heaped. 

 (Hutchison.) 



