12 PROC. ENT. SOC. WASH., VOL. 21, NO. I, JAN., 



On removal all the lice were dead and soon took on a dark brown 

 color and shriveled appearance. The eggs were returned to pill 

 boxes and kept in an incubator at 30 C. 



The hatching record obtained was: 



A 102 eggs 69 hatched 67 . 6% 



Check 75 eggs 70 hatched 93 . 3% 



B 130 eggs 102 hatched 78.4% 



Check 64 eggs 35 hatched 54 . 7% 



The results show that the wash and rinse in gasoline may be 

 counted on to destroy adult and immature stages of lice, but that 

 a high percentage of the eggs may survive a total period of one- 

 hour immersion. 



It was thus shown that the high temperature of the dry tumbler 

 is an essential factor in the dry cleaning process for the destruction 

 of the nits. Since the specifications above quoted require the 

 use of the dry tumbler by those doing contract work for the 

 army, it may be stated positively that the complete process is 

 effective in destroying both the lice and their more resistant 

 eggs. Under other circumstances, however, it is possible that a 

 dry tumbler might not be used, but that the clothing after ex- 

 traction might be dried in the open air or in a drying room in which 

 temperatures might be too low to render destruction complete. 

 With this consideration in mind we conducted further experi- 

 ments to determine whether the washing process itself could be so 

 modified as to insure complete destruction of the eggs without 

 depending at all on high temperatures. 



In view of the probability that an oil heavier than gasoline 

 would kill vermin more quickly, it was decided to try washing 

 in a heavier oil and then rinsing in gasoline. 



The gasoline used in the above experiments had a specific 

 gravity of 60 Baume. Kerosene gives a hydrometer reading of 

 about 45 Baume. By mixing kerosene and gasoline in approxi- 

 mately equal parts, we obtained an oil of about 52 Baume. 

 This was used in the following experiments as the washing fluid: 



Experiment 4. Gasoline-kerosene wash only. 



One O. D. wool coat with eggs in the pockets was 



Washed 30 minutes in 52 oil at temperature of 15 C. 



ca. 4 oz. dry cleaning soap, 

 ca. 2 oz. ammonia. 



The eggs were then removed from the pockets and were not 

 subjected to any further treatment, but were partially dried by 

 blotting with dry cloth and returned to pill boxes and kept in the 

 incubator at 28-30 C. 



