PROC. ENT. SOC. WASH., VOL. 21, NO. I, JAX., 1919 



15 



body of infested persons. The results of our tests show clearly 

 that neither gasoline nor gasoline-soap emulsion are of any value 

 in destroying nits. 



In these as in previous tests eggs of known age obtained from 

 laboratory reared animals were used. Pieces of cloth to which the 

 eggs were attached were immersed in the oil for varying periods of 

 time, and on removal were dried between blotters (thus ap- 

 proximating the extraction of the dry cleaning process) and re- 

 turned to pill boxes and kept in the incubator at a temperature of 

 28-30 C. 



Experiments with Gasoline, 60 Baume. 



Temperature 

 of oil. 



Number of 

 eggs. 



Age at Number Percentage 

 treatment, hatched, hatched. 



Treat rnent. 



Immersed for 

 period of 



30 minutes 



1 hour 



1 ' ''._. hours 



12 hours 



3 hours 



4 hours 



21 hours 



l'(i' '.hours 23 



50 hours 



52 '/z hours 23 



54 hours . . 



In another series we used a mixture of about 2 parts gasoline 

 and 1 part kerosene having a specific gravity of 56 Baume. 

 Hatching has occurred in all tests after immersion for periods of 

 from two minutes to seventeen hours. Longer immersion tests 

 have not been completed and the minimum time required to 

 effect destruction of the eggs is as yet undetermined. 



When gasoline and kerosene are mixed in approximately equal 

 parts, the resulting mixture has a specific gravity of 52 Baume. 

 Tests with this mixture showed 2.6% hatching after a 5-minute 

 immersion, but no hatching after immersion periods of from 

 10 minutes to one hour. 



A 48 Baume mixture (about 2 parts kerosene and 1 part 

 gasoline) killed all eggs after lo minutes or longer periods of im- 

 mersion. After 10 minutes, 2 out of 240 eggs or 0.8% hatched; 

 1.2', hatched after 2 minutes' immersion. 



The kerosene used in this series gave a hydrometer reading of 

 44 Baume. The following records will be of interest for com- 

 parison with gasoline: 



