22 



BULLETIN 96*7, IT. S. DEPAETMENT OF AGRICULTURE. 



used is indicated at the heads of the columns, with its strength in 

 pounds to so many gallons of water. With Paris green an equal 

 quantity of quicklime was used. 



Table 1. 



-First experiment in tlie use of arsenicals, contact insecticides, and 

 repellents against blister beetles; begun June 30, 1913. 





Number of beetles dead after 



spraying 



Date. 





with— 















Paris 



Zinc 



Lead 



Bordeaux 





green. 



arsenite. 



arsenate, 



mixture. 





1-1-25. 



1-20. 



1-12*. 



4-4-50. 



Julyl.. 



















2.. 



6 



3 











3.. 



10 



s 











i.. 





10 





 

 5 





 



1 



5.. 





7 













When the experiment was discontinued the beet sprayed with Bor- 

 deaux mixture was defoliated with only one beetle dead, and the one 

 sprayed with lead arsenate was badly damaged with only five of the 

 beetles dead. Lead arsenate made such a poor showing that its 

 strength was doubled in the second experiment. 



Table 2. — Second experiment in the use of arsenicals, contact insecticides, and 

 repellents against blister beetles; begun July 7, 1913. 



Date. 



Number of beetles dead after spraying 

 with— 



Paris 

 green, 

 1-1-25. 



Zinc 



arsenite, 



1-20. 



Lead 



arsenate, 

 l-6i. 



Bordeaux 



mixture, 



4-4-50. 



July 8. 

 9. 

 10. 

 11. 





 3 

 10 





 10 





 2 

 8 

 10 





 

 

 3 

 5 





12. 















The beets sprayed with Bordeaux were again badly defoliated, 

 but the increased strength of lead arsenate prevented much damage. 



Table 3. — Third experiment in the use of arsenicals, contact insecticides, and 

 repellents against blister beetles; begim .July 22, 1913. 





Niunber of beetles dead after 



spraying 



Date. 





with— 















Paris 



Zinc 



Lead 



Bordeaux 





green. 



arsenite. 



arsenate. 



mixture, 





1-1-25. 



1-20. 



1-10. 



4-4^50. 



July 24. 



1 







1 







25. 



3 



2 



1 



2 



26. 



7 



5 



2 



2 



28. 



10 



7 



4 



7 



29. 

 30. 





10 



6 



7 



8 

 8 









