A MAGGOT TRAP IN PRACTICAL USE. 9 
and stables in the immediate vicinity, some of these marked flies 
found their way to the college barn. Here two of this lot were 
recovered within the first 24 hours, and a third one during the third 
24-hour period. That no flies were recovered at the kitchen is to be 
explained by the fact that the kitchen was closed and there was 
nothing there to attract flies. 
A second lot of about 500 flies, sprayed with rosolic acid, were liber- 
ated at the dairy barn (A) of the experiment station, 700 yards due 
east from the college stable. The distance from the kitchen is slightly 
less. They were liberated at 3.30 p. m. September 1. On September 
3 two marked flies were found on papers exposed at the dairy barn, 
but none was recovered at the college stable or kitchen. A strong 
southwest wind was blowing at this time and may have had some 
influence on the result. It is hardly to be doubted that when the 
kitchen is in use numbers of flies from this source are attracted to it. 
The manure pile back of the dairy barn was found to be heavily 
infested at all times during the summer, and flies bred out here by the 
thousands. 
In a third experiment about 800 flies marked with powdered red 
crayon were liberated on September 15 at the stable marked by 
the letter C (fig. 1). Within the first 24 hours 11 marked flies were 
recovered on fly papers at the garbage pails, and two more during 
the second 24-hour period after liberation. No marked flies were 
recovered at the college stable in this experiment. The kitchen was 
in use at this time, and it must be considered significant that the 
flies were recovered only at the kitchen, although they had to pass 
right by the stable. This indicates the sharp rise in fly counts at 
the kitchen when it reopened in September. 
The same thing happened on September 22. A lot of about 600 
flies sprayed with rosolic acid had been liberated on September 21 
near the stable marked on the map by the letter D (fig. 1). None of 
these were recovered at the college stable, but three were found within 
the first 24 hours on papers exposed on the garbage pails at the 
kitchen. 
These few experiments indicate that a large number of the flies 
which congregate at the college kitchen and stable come from near-by 
breeding grounds other than the manure pile at the college barn. 
And it may be said that a reduction of from 67 to 76 per cent in the 
average number of flies, in spite of the proximity of these other 
breeding places, speaks well for the efficiency of the maggot trap. 
SOME DEFECTS OF THE MAGGOT TRAP. 
The experience during the past season with the platform maggot 
trap has directed attention to certain defects in its practical working. 
These defects, however, are not of such a serious nature that they 
