14 BULLETIN NO. 200, U. S. DEPARTMENT OF AGEICULTUKE. 



aerobic fermentation. This method is used to a considerable extent 

 in parts of France and Germany and is fully discussed by Ringelmann. 

 A cistern is provided into which dram all the liquids from the stables, 

 and the manure heap is watered by pumping the liquid manure from 

 the cistern from time to time. 



It is the writer's intention here merely to point out that the disposal 

 of manure on the platform maggot trap is but a sHght modification of 

 the method just mentioned. Figure 4 differs from a diagram given 

 by Ringelmami only in the platform and in the outlets through which 

 the drowned larvae may be washed into the cistern. Here is shown 

 the cistern hi which the liquid manure collects. Watering with the 

 hquid manure adds to the heap the valuable constituents of the urine 

 and promotes the anaerobic fermentation. If it is true, as just 

 suggested, that lack of oxygen and the presence of carbon dioxid 

 render the manure unfavorable for the development of the larvae, 

 it follows that compact heaping and watering, by excluding air and 

 increasing the moisture content, also insure the greatest percentage 

 of migration. As a matter of fact, compactness and high moisture 

 content are the very factors which make the maggot trap most 

 effective, whether the explanation is to be found in the temperature, 

 or moisture, or lack of oxygen. 



CONCLUSIONS. 



In this paper we have described the structure of, and the method 

 adopted in using, a platform maggot trap. All the manure from a 

 stable in which three horses were kept was stored on this platform. 

 The results obtained during August and September seemed to show 

 that at least 98 per cent of the larvae breeding in this manure were 

 destroyed. Fly counts made before and after the trap was installed 

 indicated an average reduction of from 67 to 76 per cent. That the 

 reduction of flies did not correspond to the percentage of larvae 

 destroyed was probably due to the presence of several other breeding 

 places weU within the range of fhght. 



Two difficulties were experienced in the practical working of the 

 trap, viz, the accumulation of a certain amount of straw and debris 

 on the floor under the platform and the breeding of mosquitoes 

 in the water used to drown the fly larvae. It was also found that 

 low ah' temperatures hinder migration and consequently decrease 

 the efficiency of the trap. 



Among the merits of the maggot trap were mentioned (1) the com- 

 paratively small initial cost and absence of money outlay necessary 

 for its maintenance, (2) the very small amount of additional time or 

 labor required m its operation, (3) the ease with which wagons 

 or manure spreaders can be loaded from the platform, and (4) its 

 adaptabflity for use at stables where the daily production of manure 



