W2 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 1 5 



of the eggs escaped destruction. Unsatisfactory results were secured 

 with the use of 8.6 grams per animal of derris and tobacco dust (one 

 to ten) on four other hosts. Five heavily infested calves were treated 

 by dust gun with 3.5 grams per animal of derris and wheat flour (one 

 to three) . Four days later a few living lice in all stages were still present. 

 Derris and flour in proportion of one to five was applied with a dust 

 gun on seven additional calves on Feb. 14, the infestation ranging from 

 light to heav^^^. The final examination of these animals was made on 

 March 9. Four of them appeared to have all lice destroyed while two 

 showed a very few living lice and one a moderate number. 



Three animals were treated Feb. 14 and 15 with derris and flour 

 (one to twenty) applied with a shaker can. About one ounce of the 

 m.ixture was used per animal. On March 9, one of these was completely 

 free of living lice and a few were present on the other two. Five animals 

 were dusted with a hand atomizer on Feb. 14 and 15, using derris and 

 flour in proportion of one to ten, 16.2 grams per animal. On Feb. 16 

 very few live T. scalaris were observed and on March 1 and 9 but a 

 single immature specimen was found alive. 



Owing to the fact that sodium fluoride has been shown by us to be 

 very effective against T. scalaris when applied in the dust form, and with 

 a view to developing a powder which would be one hundred percent 

 efficient against all lice on cattle, a mixture of equal parts of derris and 

 sodium fluoride was dusted with a gun on 16 calves and yearlings on 

 Feb. 24. About one and three-sixteenths ounces were used per animal. 

 On March 9 and on subsequent dates not a single live louse could be 

 found upon thorough examination. 



On May 18, 1920, two calves which were heavily infested with T. 

 scalaris were treated at Lafayette, Indiana, with pure derris powder, 

 one ounce per animal applied with a dust gun. All lice were observed 

 to be dead on May 22 and the eggs were apparently killed. On June 5 

 no living lice were found and all of the eggs appeared to be dead and 

 collapsed. Three other moderately infested calves were treated by 

 shaker can with derris and flour, equal parts. Two received one ounce 

 each and the other one and one-half ounces. Four days after treatment 

 all lice and eggs were apparently killed, and on June 5 not a living speci- 

 men was found. 



Use of Derris Against Anaplura 



The use of derris has been given a fairly extensive test against two of 

 the common sucking lice of cattle, namely Linognathus vituli L. and 

 Solenopotes capillatus End. 



On Feb. 15, 1921, seven calves, most of which were heavily infested 

 with L. vituli, were treated. Two of these received derris and flour 



