Farmers' Bulletin 73^. 



In order to figure the distance around the base of a cone of any 

 given diameter multiply the diameter by 3.1416 or 3f. 



The height of the legs of the trap, the height of the cone, and the 

 size of the aperture in the top of the cone, each are of importance 

 in securing the greatest efficiency. 



OTHER roR:srs of conical traps. 



A modification of the previously described trap has been made by 

 Mr. D. C. Parman of the Bureau of Entomology. The principal 

 point of advantage in this type is that it can be made more quickly 

 and with fewer tools. The principles and dimensions are the same, 

 the most striking difference being the absence of a wooden top. A 



single hoop with the 

 thick edge down 

 forms the upper 

 frame of the cylinder 

 and the entire top is 

 made of screen. A 

 circular piece of 

 screen with a diameter 

 about 3 inches greater 

 than the diameter of 

 the cylinder is cut; a 

 hoop with a diameter 

 equal to the inside of 

 the top of the trap is 

 then made of heavy 

 wire and laid upon 

 the disk of screen and 

 the edges of the screen 

 bent in over it. .By 

 folding in and crimp- 

 ing the edges of the 

 wire over the wire 

 hoop it will remain in position without difficulty and the edges of the 

 screen disk are used to lift the top of the trap out for emptying flies. It 

 is important to have the screen top fit the inside of the cylinder very 

 snugly at all points. If there is any space left where flies can escape 

 it is a. good plan to bind the edge of the top with a strip of burlap. 

 This not only helps to close the openings but keeps the hoop in place 

 and aids in removing the top. Another difference is that the screen 

 forming the sides of the cylinder is placed on the inside of the hoops 

 and legs, the frame being built first and then the cylinder formed by 

 tacking the wire on the inside of the hoops and nailing in along the 

 upright strips and against the wire short pieces of laths with their 

 upper ends against the lower edge of the hoop forming the top of 



< zr '-^ 



Fig. 4. — Tent flytrap. When the trap is sot up the screen 

 box, A, fits on the base, B, and two pans of bait are 

 placed beneath the tent. C, Hole in screen at apex of 

 tent. 



