188 Psyche [December 
two treatments at weekly intervals. It was not ascertained, how- 
ever, if one application would be sufficient. 
More recent work included tests of a considerable number of 
insecticides. ‘The results of the early tests with arsenical solution 
were completely borne out and it appeared that all forms of both 
the biting louse (7. scalaris) and the long-nosed ox louse (Linog- 
nathus vituli L.) were destroyed with one dipping. In one ex- 
periment with arsenical solution of one-half the normal strength 
both adults, larvee, and eggs of T. scalaris were destroyed. The 
use of this strength against the long-nosed ox louse did not ac- 
complish complete destruction. The action of the arsenical so- 
lution against the biting lice was quite prompt, but the sucking 
lice were killed more slowly, as in the case of ticks. 
All of our tests prove that the biting lice are quite susceptible 
to the action of caustic or poisonous substances. ‘They seem to be 
killed uniformly more easily and quickly than the sucking species. 
In a series of experiments against the biting lice of cattle the fol- 
lowing substances were used in addition to arsenical dip: Kerosene 
emulsion (2 gals. kerosene, 4 lb. laundry soap, 1 gal. water, re- 
duced 1 to 8 and 1 to 12); flowers of sulphur (3 lb. per animal); 
40 per cent. nicotine sulphate (1 to 800); soap and water (1 oz. 
per gal.); sodium fluoride (commercial, 90 to 98 per cent.) as dust 
and dip. All of these substances, with the exception of the soap 
and water, killed all stages. The soap and water destroyed 
everything but the eggs, which hatched successfully. 
The sodium fluoride (97 to 98 per cent.) was used as a spray at 
the rate of one ounce and also one-half ounce per gallon. In both 
of these strengths all stages were promptly destroyed. When 
applied as a dust the material was put on with flour in the propor- 
tion of one ounce to five ounces of flour, six ounces of this mixture 
being used on a yearling. Three ounces of sodium fluoride were 
applied to an animal with a shaker and the material worked into 
the hair, and in another test one ounce was applied with a bellows 
dust gun. In each of these tests the destruction was complete. 
A number of experiments were also conducted with the use of 
sodium fluoride against the biting dog louse (Trichodectes latus 
Nitzsch). Some of the animals treated were very heavily infested 
and covered with sores evidently caused by the presence of the lice. 
In some tests the material was applied by hand with a dust can, 
