12 



Farmers' Bulletin 73^. 



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 

 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 Avith the side of the trap — that is, parallel with the 



7-^ 



. Ch 



Fig. 7. — IIodRo typo window trap. At left, trap with end removed to show construction; 

 at right, cross section of trap placid in a window. A, I'nd of trap. B, T'ppcr side of 

 folds in screen. (', Lower side of folds in screen. D, Portion of end of trap sawed out 

 and returned after attachinji screen. E, Holes along apex of folds. F, Door for remov- 

 ing dead flies. O, Window sill. II, Upper window sash. I, Inside entrance for flies; 

 0, Outside entrances. 



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 D returned 'a,Her the screen has been 

 tacked along tlie edges. Along the apex (inner edge) of each fold is 

 punched a series of holes E about one-half inch in diameter and 1 inch 

 apart. Th© apices of the folds on either side of the window should 

 not be directly opposite. A narrow door F opening downward on 

 hinges should be made on one side of the trap at the bottom for 

 removal of the dead flies. The entire trap is fastened to the win- 

 dow by hooks so that it may be readily taken off. An additional 

 trap]iing feature may be added by ])roviding a tent trap fitted in the 

 bottom of the box. A narrow slit is left alone the base to allow the 



