244 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 larvie and puparia of this species have been 
figured by the writer, but the full life history has been 
carefully studied by Xewstead. 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 72 0 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. Xewstead 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- 
