October, '12] WASHBURN: MINNESOTA FLY-TRAP 401 



seems to make no difference as regards their efficiency. The screen used 

 is ordinary wire mosquito screen and that and the small amount of 

 lumber required made each trap cost us 41c. for material. Made in 

 large numbers the cost would be very much less. A skillful carpenter 

 could easily construct this apparatus in two or three hours. The 

 upper oval part (c) serves as a receptacle which the flies enter through 

 the opening in the top of the middle portion (6) made of screen and 

 shaped like the roof of a house. Under this is the base board (a), 

 upon which rest two tin bait pans. The space between the baseboard 

 and the middle portion is about one-half inch, and between this and 

 the bait pans through which flies enter pans, about one-fourth of an 

 inch. 



The record made by one of these traps is in part as follows: 



Hear of dining hall on campus, two days, 3000 flies 



Dairy Barn, one day, 1700 flies. 



Rear of dining hall, five days, 13,000 flies 



Same place, three days, 6000 flies 



Same place, one day, 4200 flies 



-On back porch of a dwelling not far from a stable 

 where a few horses are kept, two days, 8700 flies 



Same place, one daj'', 12,000 flies 



Same place, one and a half days, 18,800 flies 



Fig. 9. Cross section of trap. 



Bait: This is an extremely important factor in the use of this trap, 

 and we find we have to qualify to a certain extent previous recom- 

 mendations in this regard. Ordinarily, we believe that bread and 

 milk, frequently renewed, is the best bait for this and other fly traps, 

 but under certain conditions, this is not as attractive as it might be. 

 For example: We loaned one of these traps to a dining hall association 



