A MAGGOT TRAP IN PRACTICAL USE. 5 



But this number does not represent all that dropped out of the manure 

 mto the water below. A flock of young turkeys roamed at large 

 during the sunomer over the college grounds and adjoining fields. 

 Having once found the maggot trap they made frequent visits and 

 were seen to devour the larvae with great avidity, sometimes com- 

 pletely clearing the floor except where the water was more than 2 or 3 

 inches deep or when it was so badly discolored as to conceal the larvae. 

 Sparrows also were seen frequently on this floor, but one could never 

 get close enough to see whether they actually devoured any larvae or 

 not. It is more than likely that they did. The actual number of 

 larvae which were destroyed by the maggot trap was undoubtedly 

 much gi"eater than 112,000. 



After October 1 the writer and an assistant examined all the manure 

 on tliis platform in search of puparia. The manure was tlu-own off, 

 a few bushels at a time, onto a smooth concrete surface near by and 

 very carefully examined, all straw being shaken out and all solid 

 parts being finely broken up. In a very literal sense this was like 

 looking for a needle in a haystack. A few scattered puparia were 

 seen in various parts of the heap, but in only two spots were they to 

 be found in the characteristic clusters or "nests" which can be found 

 so readily at the edges of manure piles on the ground. These two nests 

 were found at the end of the platform where the most recent additions 

 had been. made. The manure at this end had not been sprinkled 

 with water after the day it was put on. Failure to keep this moist 

 as long as larvae were present is, in the writer's opinion, the explana- 

 tion of the pupation in this part. One nest contained about 400, 

 and tlic second about 700 puparia. Allowing for some that may have 

 escaped notice, the number of puparia may be given in round numbers 

 as 1 ,oOO. No larvae whatever were found in any part of this heap, the 

 oldest part of which had been on the platform for two months, and 

 even the freshest portion of which had been standing for at least 10 

 days before it was examined. If, then, 1,500 represents the total 

 nuiiiljer which pupated in the manure and 112,000 the number 

 whi'h was destroyed by drowning, it shows a percentage destruction 

 of about 98.5 per cent of the possible total. This is illustrated in 

 figure 2, above. Taking into account the larvae devoured by 

 turkeys, etc., it is probable that the effectiveness of the trap could be 

 rated as above 99 per cent. 



In a former bullftiri the claim was made that manure will be prac- 

 tically free from maggots after standing 10 or 12 days. Special 

 attention was given to this point during the course of the experiment, 

 iind all observations 1 ended to support the claim. Moreover, tliere 

 was no cvidcnee that larva; (ivcr migrate(l from the fresher ])orti()ns 

 • of the manur(5 to the oidcr |)iiits to |)ii|)atc. That old manure 

 do('s not serve as a br(;eding pluce for (li(!s is a point that (h^serves 



