14 PROC. ENT. SOC, WASH., VOL. 21, NO. I, JAN., 1919 



The results of this series of experiments may be stated as fol- 

 lows: 



1. A thirty-minute wash in 52 Baume oil, when not followed 

 by rinsing or any treatment other than extraction, prevented all 

 eggs from hatching (Experiment 4). 



2. When a 15-minute rinse in 60 Baume gasoline followed the 

 15-, 30-, and 45-minute wash in the 52 Be. oil, a considerable 

 percentage of eggs hatched in each case. 



3. The records of Experiments 5 to 7, as tabulated below, show 

 a progressive decrease in the percentage of eggs hatching as time 

 of the washing period is increased. 



IVriod of time ir> washing fluid 

 of 52 Baume, followed by 

 15 minutes' rinse in 



60 Baume oil. 

 Untreated r~ 



checks. 15 min. 30 min. 45 min. 



Percentage hatching of eggs 3-5 days old 66% 25% 14.3% 10.8% 

 Percentage hatching of eggs 1-3 days old 95% 62.1% 47.1% 28,'."', 



4. It is concluded therefore, that washing in heavier oil 

 (52 Baume), when followed at once by rinsing in gasoline, is of 

 no practical value as far as the destruction of the eggs is con- 

 cerned. 



It was suggested by a correspondent (J. E. Fox, Great Falls 

 Dye House, Great Falls, Mont., letter dated October 14, 1918) that 

 infested clothing be soaked in kerosene for 24 hours, then ex- 

 tracted and dry cleaned in the usual manner. He states that after 

 some experiments along this line some years ago, this plan was 

 adopted by his firm, as it appeared to kill both lice and nits and 

 it offered a further advantage in that certain greases responded 

 more readily to the kerosene than to gasoline. We did not have 

 opportunity to try out this method on a practical scale, but in 

 some laboratory tests detailed below it was found that a 24-hour 

 soaking in kerosene followed by rinsing in gasoline was not effec- 

 tive in preventing all hatching of eggs. 



Laboratory Tests with Oils. 



A series of laboratory tests was carried out in order to de- 

 termine more exactly the killing power of oils of different specific 

 gravity. It was considered especially important to check up the 

 results with gasoline. Kinloch (Brit. Med. Jl., No. 2842, pp. 

 1038-41. June 19, 1915) states that "it has so far been found 

 impossible to revive the lice or rear the eggs after immersion in 

 petrol for one minute." Grubbs (1916, Reprint No. 370 U. S. 

 Public Health Reports) has evidently been mislead by Kinlock's 

 statement in devising a gasoline-soap emulsion for bathing the 



