FLIES THAT FREQUENT HOUSES 43 



ally depositing their eggs in numbers in piles of heated 

 lawn grass alongside of a cucumber frame in a garden. 

 Howard has reared the fly from horse and cow manure 

 and remarks, "I judge from the fact that it is attracted 

 to human excreta that it may become a carrier of in- 

 testinal disease." 



The eggs hatch in two to three days under temperatures 

 ranging from 65 degrees to 72 degrees F. The larvae 

 demand a good deal of moisture and an absence of light 

 for their best development. Under these conditions they 

 attain their growth in two to four weeks. Evidently 

 where soil is available beneath the manure the larvae 

 bore down to it and pupate in the earth. The pupal stage 

 lasts 6 to 26 days. The complete life cycle is, therefore, 

 passed through in from 3 to 4 weeks under favorable con- 

 ditions of light, heat, and moisture. 



F. C. Bishopp records a very interesting outbreak of the 

 biting house-fly in Texas. The flies, in this case, were 

 found breeding in great numbers in straw stacks. From 

 these situations they swarmed on the live stock, causing 

 serious injury to horses and cattle. Moreover, investi- 

 gation and inquiry disclosed the fact that previous out- 

 breaks of this fly had occurred in former years. 



Bishopp found the flies breeding in oat, rice, barley, and 

 wheat straw, and in horse manure and cow manure. In 

 the straw stacks, the maggots were found in the wet 

 rotting straw. When the larvae attained their growth 

 they pupated in the straw. A single fly was seen to make 

 three depositions of eggs, laying a total of 278 eggs. The 

 total period from egg to adult varied from nineteen to 

 forty-three days. 



Howard, in his book on the house-fly, relates an in- 



