26 THE STABLE FLY. 
across the window, one toward the bottom and one toward the top. 
The ends of the screen are then securely tacked and a series of small 
holes punched along the inner edge of each of the folds. The trap- 
folds and ridge must not be too sharp or flies will not go up to 
the angle. They should not be less than 45°. The flies, in trying 
to go in and out through the window, crawl into the folds and 
enter the holes at the apex, but never escape, as on the inside the 
holes are along the projecting ridge. Prof. Hodge states that a 
trap set in a window in a basement barn near a cow within caught 
nearly 5 quarts of flies from July 1 to November 1. The stable fly 
constituted 90 per cent 
of these flies, this being 
practically all that ap- 
peared on the place. 
This trap is inexpen- 
sive and can be made 
by anyone with a box, 
or box lumber, and 
screen wire. It is es- 
pecially well adapted 
to well-made barns 
where the flies do not 
have numerous places 
for entrance and exit. 
It is also more applic- 
able to small barns in 
which animals are kept 
more or less constantly 
than to large dairy 
barns where the cows 
are brought in only at 
milking time. Under 
thelatter conditions the 
flies enter the barns on 
the cows and many 
remain on the walls of 
the barn until after the cattle have been turned out. In some cases 
where flies are concentrated in dairy barns in this manner they have 
been driven out by forcing live steam into the building from the boilers 
used for sterilizing purposes. Where such arrangements are made the 
flies may be caught in such traps as the one described, as they are en- 
deavoring to escape from the barn, which should first be tightly closed. 
If such barns are tightly closed, as above, during the light part 
of each day, the flies will practically all ‘‘catch themselves” in trying 
to escape through the trap-window or windows. 
540 
Fig. 9.—The Hodge flytrap fitted toa barn window. (After Hodge. ) 
