196 THE HOUSE FLY—DISEASE CARRIER 



lime and spread out in a large tin pan. Two days later 

 most of the larvae were found to have hardened into 

 puparia, but none was killed. 



September 4th, eight quarts of fresh horse manure 

 containing larvae were spread out in a tin pan and 

 sprayed with one pint of kerosene washed down with 

 one quart of water. September 7th, three days later, 

 twenty per cent, of the larvae were still living. 



September 7th, eight quarts of fresh horse manure 

 containing house fly larvae were placed in a tin pan, 

 sprayed with one pint of kerosene, washed down after- 

 wards with one quart of water. The manure was then 

 mixed and a little more water poured on. Twenty-four 

 hours later every larva in the mass was dead. 



October 15th, one pound of chloride of lime was 

 mixed with eight quarts of well-infested horse manure, 

 which w^as kept in a bucket. October i6th, ninety per 

 cent, of the larvae were dead, the remainder having 

 burrowed into the large lumps of manure. October 

 1 8th, no living larvae could be found. 



October 21st, one-quarter of a pound of chloride of 

 lime was mixed with eight quarts of fresh horse ma- 

 nure and kept in a bucket. This treatment was unsuc- 

 cessful and only two larvae were killed. 



Herms also conducted certain experiments in this 

 direction at the University of California. He found 

 that the fly larvae are extremely tenacious of life, and 

 that insecticides which will kill them must be strong, 

 in fact from two to five times as strong as those which 

 are useful against other insects. He writes, ''Chem- 



I 



