THE HOUSE-FLY 27 



to the board (6). The oval part (c) covered with wire 

 screen is placed over the roof-like traps to receive and 

 hold the flies. The three parts are held together by 

 the hooks at the end (Fig. 10). In Fig. 11 is shown a 

 cross section of the trap, which will aid in explaining 

 the construction. The space between the baseboard 

 and middle portion is about one-half an inch. The 

 bait should be renewed occasionally and not allowed 



FIG. 10. End of trap, FIG. 11. Cross section 



showing hooks. of trap. 



to become dry and unattractive. The flies that gather 

 in the upper, oval part of the trap may be killed by pour- 

 ing boiling water on them. Probably galvanized wire 

 screen will withstand the effects of water and general 

 usage without rusting better than the ordinary painted 

 wire. 



With this trap, the Minnesota people caught in a dairy 

 barn in one day, 1700 flies ; dining hall, rear of building, 

 two days, 3000 flies; same place, five days, 13,000 flies; 

 on the back porch of a dwelling house not far from a stable 



