2U THE HOUSE FLY— DISEASE CARRIER 



bris burned within forty-eight hours after the com- 

 pletion of the threshing, the ashes being used for fer- 

 tilizing purposes. It turned out that there was an old 

 provincial law in the province of Santa Fe ordering 

 the burning of the debris after threshing, but it had 

 not been carried out during recent years, and therefore 

 the Stomoxys multiplied until this veritable plague en- 

 sued. In 1888 this Stomoxys made its appearance in 

 extraordinary numbers near Salem, Oregon, and it is 

 altogether likely that there was some similar reason 

 for its extraordinary abundance that year. At that 

 time, however, its true breeding places were not known 

 and the cause of the outbreak was not found. 



There are undoubtedly many substances in which 

 the biting house fly breeds, and it evidently requires 

 about the same conditions as does the true house fly. 



The larvae and puparia of this species have been 

 figured by the writer, but the full life history has been 

 carefully studied by Newstead. He found that the eggs 

 are laid in an irregular heap and that the average num- 

 ber deposited is about sixty. The egg is much like that 

 of the house fly, and is one millimeter long. It hatches 

 in from two to three days in an average temperature 

 of y2° F. in the day and 65° F. in the night. The 

 larva need not be described, since it is similar to that 

 of the house fly. Newstead found that in this stage 

 they lived from fourteen to twenty-one days, but that 

 the absence of excessive moisture and the admission of 

 a little light materially retarded development, which 

 then extended over a period of thirty-one to seventy- 



