HOUSE FLIES. 19 
manure, drop into the water below, and are drowned. Each week 
the plug is removed from the pipe, and all the maggots are washed 
into the cistern. The floor is then cleaned of any solid particles by 
means of a long-handled stable broom or by a strong stream of water 
from a hose. The pipe being again plugged, the floor is again partly 
filled with water and the trap is ready for another week’s catch. A 
platform of this size will hold the manure accumulating from four 
horses during the period of four months, or about 20 days’ accumula- 
tion from 25 horses, if the heap is well built and made at least 5 feet 
high. 
Experience with maggot traps has brought out the following 
points: In the first place, the trap is more effective when the manure 
is kept compactly heaped and well moist. This is to be explained by 
the fact that the larve seek a comparatively dry place in which to 
Ut. Vit “Uitte dd@ NG 
Iie. 15.—Imaginary cross section of an arrangement suggested for use where manure pro- 
duction is large. a, Pump; ¢, concrete floor and walls of cistern; 0, outlet pipes leading 
from flocr of maggot trap to cistern; p, platform maggot trap; f, cistern for liquid 
manure; g, ground level. (From Hutchison.) 
pupate, and crawl away from wet manure. <A cistern should be built 
close to the trap, and a pump fitted so that liquids can be pumped 
onto the heap. (Fig. 15.) Each day, after the litter from the stable 
has been thrown on the heap, just enough water should be added to 
moisten it thoroughly without causing leaching. The ideal arrange- 
ment would be to have water-tight floors in the stalls and drains 
leading to the cistern. The liquid manure collecting in the cistern 
could be pumped on the manure heap, thus not only maintaining the 
moisture content necessary to insure the greatest amount of migra- 
tion, but also adding to the manure the valuable constituents of the 
urine. It happens, too, that keeping the manure carefully heaped 
and watered promotes the anaerobic fermentation and tends to 
prevent to some degree the loss of ammonia and gaseous nitrogen. 
In the second place the platform should stand not less than 1 foot 
above the concrete floor. This is to facilitate cleaning the floor of 
maggots and the débris which unavoidably accumulates there. The 
