BULLETIN OF THE 



No. ie« 



Contribution from the Bureau of Entomology, L. O. Howard, Chie 

 January 22, 1915. 



(PROFESSIONAL PAPER.) 



CACTUS SOLUTION AS AN ADHESIVE IN ARSENICAL 



SPRAYS FOR INSECTS. 1 



By M. M. High, 

 Entomological Assistant, Truck Crop and Stored Product Insect Investigations. 



INTRODUCTION. 



In the application of arsenical sprays against insects with biting 

 mouth parts the object in view is, of course, to protect the plant or 

 plants from insect ravages by poisoning the foliage, so that the insects 

 will, in feeding, take into their system enough of the poison to pro- 

 duce death. Some arsenicals, because they possess a higher percentage 

 of free arsenic, act more quickly in this direction than others, but 

 these are, as a rule, injurious to most plant foliage, unless mixed with 

 some agent that will counteract the free arsenic and produce a more 

 uniform distribution on the plants sprayed. Arsenicals containing 

 a high percentage of arsenious oxid generally possess only slight ad- 

 hesive powers and after a heavy dew or light rain are washed from 

 the foliage. 



Certain crops demand very prompt protection from the ravages 

 of biting insects; otherwise severe losses are almost certain to be 

 incurred, and to insure the preservation of the crop concerned it is 

 highly important that a poison with some lasting qualities, as well 

 as one quick in action, be applied. Thus it follows that an arsenical 

 must adhere to the foliage if the most favorable results are to be 

 realized. 



In 1913 and 19M some experiments were conducted for the 

 purpose of discovering a good adhesive which could be obtained 

 easily and at little expense to the grower. This adhesive has been 

 found in a cactus that flourishes in the Southwest. The variety 

 which was most extensively used in the following experiments, and 



1 This bulletin describes the use of cactus solution as an adhesive in the application of 

 arsenical sprays against the belted cucumber beetle. It is applicable to regions where 

 prickly pear is easily obtainable and for the treatment of insects of related habits, such 

 as the striped and twelve-spotted cucumber beetles, etc. 

 65966°— Bull. 160—15 1 



