GRASSHOPPERS AND OTHER INJURIOUS INSECTS OP 1911 AND 1912. 



65 



The bait is a very important factor in using this trap. It should 

 co7isist of bread and milk and frequentUj renewed. That is, it 

 should not be allowed to dry up and consequently lose its attractive- 

 ness. The flies in the upper part, or receptacle, should be killed by 



immersing that part of the trap in 

 hot water or pouring boiling water 

 over it, or in any other way devised 

 by the user and not injurious to the 

 trap itself. These dead flies may 

 be emptied out of the trap, the bait 

 renewed and the trap reset. 



We append herewith the result 

 of several difi'erent days' use of the 

 trap illustrated. These results 

 were reported to the Chief of this 

 Division by Mr. Dan Nelson, an 

 employee, who was placed in 

 charge of the traps with directions 

 to keep a careful record of the flies 

 caught: Dairy barn, one day, 

 1,700 flies; two days, 2,000 flies; 

 dining hall, rear of building, two 

 days, 3,000 flies; same place, two 

 days, 3,000 flies; same place, five 

 days, 13,000 flies; dairy barn, two 

 days, 1,800 flies; dining hall, rear 

 of building, three days, 6,000 flies ; 

 same place, three days, 5,000 flies; same place, one day, 4,200 flies; 

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



Figr. 45. 



House-fly on nipple of nursing- 

 bottle. Brues. 



Fig. 46. The Minnesota Fly Trap. 



