26 



HOUSEHOLD INSECTS 



entered the can, they naturally migrated upward through 

 the hole over which the trap was placed, being attracted 

 by the light which entered only at this place. 



Hodge argues that we should catch the first original 

 pair of flies in the spring before they lay any eggs and 

 thus escape the whole fly trouble. And he thinks it could 

 be done in some such way if every one would cooperate. 



The ordinary 

 fly traps are rather 

 small and where 

 flies are abundant 

 have to be emptied 

 too often. It is 

 sometimes desir- 

 able to have a 

 trap in which flies 

 may be caught in 

 large quantities 

 without being fre- 

 quently emptied. 

 A. M. Bull of the 

 engineering divi- 

 sion of the Uni- 

 versity of Minnesota designed a large trap of this kind 

 that has proved very successful (Fig. 9). The trap is 

 twenty-four inches long, eight inches high, and twelve 

 inches wide. It consists of three parts, a baseboard (a), 

 a roof-like trap (b), and an oval part (c). On the base- 

 board are two shallow pans to contain the bait, usually 

 milk and bread. The trap consists of two roof-like 

 screens with several openings along the ridge for the 

 flies to crawl through. These two traps are fastened 



A 



Fig. 9. — A large fly trap. 



