PREVENTIVE MEASURES 
215 
wire gauze trap was set over a hole on the sunny side 
of the top of the can. The flies crawled in, attracted 
by the odor of food, and attempted to escape by the 
only opening through which the light came, thus enter¬ 
ing the trap. 
Another form devised by Hodge had a tight can 
cover, the trap being contained within the cover. The 
trap itself forms the only entrance to the can, and the 
flies attracted by the odor enter the trap. Another 
trap devised was a wire gauze cylinder fitting over a 
tomato can, the can being filled with attractive sub¬ 
stances, and the trap being arranged so as to be scat¬ 
tered around stables or barnyards or wherever flies 
happen to be congregating or breeding. 
He made still another arrangement for a screen for 
a stable cellar or manure pit window, making a small 
hole in the screen near the top and providing the screen 
with narrow strips of tin or wood to guide the flies to 
the hole; the hole, of course, leads into a wire gauze 
trap, where all the flies that emerge will be caught. In 
the same way he made another, also provided with 
guiding strips, on the outside, and furnished with a 
trap on the inside, so as to catch all of the flies that 
might be attracted to the stable to lay their eggs. This 
latter idea he has not )^et tested, but he argues that 
if the outside flies were shut out by screens they would 
certainly find some other breeding place in which to 
lay their eggs. 
On the habit that flies have of being attracted to 
kitchens by the odor of the cooking or by the warmth 
