4 BULLETIX XO. 200, U. S. DEPARTMENT OF AGRICULTURE, 
of construction. Plate II gives another view, including also the 
outlet pipe (in this case consisting of 4-inch terra cotta) and the pump 
in place over the cistern. On account of various obstructions it was 
necessary to place the cistern some distance away from the trap, 
although, as will be pointed out later, it is desirable to have the cistern 
close to the trap and the pump so arranged as to return tjie contents 
of the cistern to the manure heap on the platform. 
THE METHOD ADOPTED IN USING THE MAGGOT TRAP. 
The maggot trap was put into operation on July 25. On this date 
the manure pile which had accumulated in front of the barn during 
June and July was hauled away and spread on the fields, so that, 
beyond the hatching out of the pupae and larvae already present, it 
ceased to exist as a breeding ground for flies. On and after July 25 
each day's production of manure was heaped on the platform. 
Beginning at the end farthest from the barn door, the manure was 
piled up to a height of from 3i to 4 feet. The heap was maintained 
at about this height, and with the daily additions it kept increasing 
in length. Plates I and II show the appearance of the heap after a 
little more than four weeks' accumulation. The platform was found 
large enough to hold a little more than two months' production of 
manure from three horses and could easily have been made to hold 
the total production for three months by making the pile higher. 
Each day, after the addition of manure and litter from the stable, 
the manure on the platform was sprinkled with enough water to 
moisten it thoroughly without causing any leaching. Water was 
run into the concrete basin below the platform, so that the floor 
beneath the manure was covered to a depth of \ inch in the shallowest 
part. Larvae migrating from the manure dropped into the water 
below and were drowned. 
At least once a week, and sometimes oftener, the water was drawn 
off from the basin into the cistern and the floor was washed clean by a 
strong stream of water from a hose. The larvae which had fallen into 
the water, together with the debris which had sifted through the 
platform or fallen from the sides, were collected at the cistern end 
of the outlet pipe in a strainer. The matter thus retained in the 
strainer was then spread out on a smooth concrete surface near by, 
and the number of larvae present was carefully estimated. The 
outlet was then plugged, and the basin again partly filled with water 
by pumping back what had run into the cistern. 
THE PERCENTAGE OF MAGGOTS DESTROYED. 
Without going into details of the weekly or biweekly counts, it 
will be enough to state that during the period from July 25 to October 
1 a total of about 112,000 dead larvae were collected in this way. 
