INSECTS INJURIOUS TO MAN AND IN HOUSEHOLD 639 



foot from the bottom, a slatted platform is constructed, the plat- 



form being a little smaller in area than the pit. On this platform 



the manure is stored. 



The manure should be 



kept wet. This may be 



accomplished by pump- 



ing or sprinkling water 



over the surface daily. 



This process also keeps 



water in the pit. When 



the larvae migrate they 



fall into the pit and are 



drowned. Experiments 



have shown that from 



95 to 99 per-cent of all 



the larvae can be de- 



stroyed in this way. 



After about ten days the 



manure is no longer suit- 



able as a breeding place 



and it may be removed 



to make room for more. 



Details 



XI 



FIG. 551. Conical hoop fly trap. (After Bish- 



PP> u - s - De P t - of A &-) 



may be secured irom the publications cited. 

 Larvae are sometimes poisoned in their breeding places by 

 treating the manure with powdered borax or hellebore, dry or in 



water. About one pound of 

 borax to 16 cubic feet is the 

 strength required, whileslightly 

 less hellebore will give good 

 results. Careless handling of 

 the borax, resulting in the un- 

 even distribution or the use of 

 too much may result in injury 

 to plants fertilized with the 



manure. 



FIG. 552. One of the green-bottle flies T ,,.,. ,, , 



(Lucilia caesar}. Much enlarged. ln addition to the above 

 Howard, U. S. Dept. of Agr. methods we have the time 



honored fly-papers, fly-killers, window-screens and poisons for the 

 adult flies. These can, at best, give only partial relief. 



