64 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



Pupal Stage. — The pupal stage was found to range from three to 

 at least twenty-six days in our experiments to determine this point 

 with exactness. The temperature is an important governing factor. 

 It is probable that its influence on the length of the pupal period is 

 e'ven more marked than on the length of the larval stage as the pupae 

 are usually more removed from the heat of the manure and they have 

 no way of accommodating themselves to changes in temperature, as 

 do the larvae. In one of our hibernation experiments at Uvalde, 

 Texas, in 1914, it appeared that a good many individuals remained in 

 the pupal stage from January 27 to April 4, or over two months. 



Breeding Material 



As has been observed by many entomologists, horse manure is a 

 very favorable breeding medium for the house fly. In Texas we have 

 found them to breed freely in the manure of the chicken, hog, goat, 

 and to a large extent in pure cow manure, provided other more attrac- 

 tive media are not present. The latter substance is not as attractive 

 as some other materials. Decaying vegetable matter and kitchen 

 refuse also form important sources for fly breeding; this is especially 

 true around cities where rather large accumulations of each substance 

 are found. At the dumping grounds around Dallas large quantities of 

 decaying potatoes were found which seemed to be ideal for house fly 

 breeding, producing countless numbers of them. Decaying melons 

 and mixtures of kitchen refuse were also found to breed considerable 

 numbers. The paunch contents of animals were found to furnish 

 favorable breeding places for house flies after the bodies of the animals 

 had been consumed by scavengers. In the grain belt of Texas, Okla- 

 homa, and the states to the north, the bases of stacks of oat or wheat 

 straw which had become well rotted were found in some instances to 

 breed many house flies. The straw during the first year after thrash- 

 ing, although in a high state of fermentation, is not favorable for house 

 fly breeding although myriads of stable flies may breed in it. Well- 

 decayed straw stacks or the remains of stacks after being burned 

 should be considered in fighting the house fly m rural communities. 

 Ensilage scattered about silos or in troughs has been found very favor- 

 able for house fly breeding, and fermenting cottonseed hulls mixed 

 with bran, etc., in the bottom of feed boxes or troughs have been found 

 to produce flies bej^ond all expectations. 



Longevity 



When considering the destruction of house flies in the adult stage 

 the question of their longevity is one of importance. A number of 

 experiments upon this point have been conducted in Europe, but httle 



