4 BULLETIN IS^O. 200^ U. S. DEPAETMENT OF AGEICULTIJEE. 



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 the 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 pupss 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 Httle more than two months' production of 

 manm'e from tliree 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 wa}^. 



