FLYTRAPS AND THEIR OPERATION. 9 
as to catch the flies as they enter or leave through the window. It 
is adaptable to barns which are fairly free from cracks or other 
places where flies may enter. It may also be used on windows of 
buildings where foodstuffs are prepared and where flies endeavor to 
enter through the windows or escape after having gained entrance 
through other passageways. All openings not provided with traps 
should be closely screened, and on large buildings traps may be 
installed in every third window. 
This trap is essentially a screen box closely fitted to the frame of 
Fic. 6,—Use of fiytrap in connection with manure bin. 4, Block of wood set in ground to 
which lever raising door is hinged. (Original.) 
a window (see fig. 7). The thickness of the box at A should be about 
12 inches. Instead of the screen running straight down over the box 
on either side it is folded inward nearly to the center of the frame 
in V-shaped folds running longitudinally across the window. One, 
two, or even more folds may be made in the screen on either side. 
The upper side of the fold B should extend toward the center almost 
at right angles with the side of the trap, that is, parallel with the 
top and bottom; and the lower side (’ should slant downward as 
shown in the drawing. The sides of the frame may be cut out at 
the proper angle and the pieces ) returned after the screen has been 
tacked along the edges. Along the apex (inner edge) of each fold is 
