2 HOUSEHOLD INSECTS 



matters that are allowed to accumulate in the vicinity 

 of human habitations and the maggots that hatch from 

 the eggs live on this decaying matter and aid in destroy- 

 ing it. Thus it must be conceded, perhaps, that house- 

 flies do assist somewhat in the removal of foul and 

 dangerous waste matters and, to this extent, are of 

 benefit. On the other hand, it has been conclusively 

 shown that this modicum of benefit is greatly over- 

 balanced by their role in disseminating dangerous dis- 

 eases. It has been shown that house-flies carry the 

 germs of cholera, typhoid fever, cholera infantum, and 

 tropical dysentery, on their feet, legs, and bodies and in 

 their digestive tracts. There can be no doubt of the 

 responsibility of the house-fly for much sickness and many 

 deaths. 



A COMMON SOURCE OF HOUSE-FLIES 



In the summer of 1910, two large piles of horse ma- 

 nure were drawn and placed in a field about twenty rods 

 south of the building in which the office of the author is 

 located and on the same side. During the months of 

 July and August the flies were so abundant in the build- 

 ing and especially in my office that screens had to be 

 used as a protection against the dreadful annoyance of 

 these pests. On investigation, the piles were found to be 

 teeming with maggots of the house-fly. In seven ounces of 

 the manure, taken from the smaller pile, 458 maggots of 

 various sizes were actually counted. Many of the smaller 

 ones must have escaped notice. The seven ounces of 

 manure was a seething mass of maggots, showing what 

 a tremendous number of flies the two piles of manure 

 could have furnished if they had been equally infested all 



