October, '22] warren: moisture and boll weevil poisoning 345 



fore an analysis is asked for. They do show, however, a large propor- 

 tion of water unsafe for use with this common type of arsenical. When 

 it becomes necessary to use alkaline or hard waters in spray work, 

 the safest plan is to substitute basic arsenate of lead for the acid type. 

 Milk of lime combined with acid arsenate of lead tends to prevent 

 danger of this kind. 



Conclusions: Hard and alkaline waters form dangerous combinations 

 with many forms of insecticides. 



Softening of hard water with chemicals is only partially successful. 

 Water softening plants, with a capacity sufficient for supplying a spray 

 outfit and for domestic purposes also, may be installed at a cost of 

 a few hundred dollars. 



The use of dusting materials, where practical, in place of liquid 

 sprays is desirable, in that the user is inependent of the type of water 

 found locally. 



Insecticides compatible with the salts commonly found in waters 

 are desirable and in many instances will prove a satisfactory solution 

 of the subject. Examples of such substitutions are, basic arsenate of 

 lead instead of the acid (standard) type, arsenical dips in Heu of cresol 

 preparations, and the stable oil emulsions which are made for use in 

 waters. 



RELATION OF MOISTURE TO INGESTION OF POISON BY 

 THE COTTON-BOLL WEEVIL 



By D. C. Warren, Georgia State Board of Entomology 



Considerable attention has recently been given to the problem of 

 poisoning the cotton boll weevil by the use of calcium arsenate. The 

 dusting method has been used and has given profitable results. 



In Bulletin 731, United States Department of Agriculture, B. R. 

 Coad concludes that "success in poisoning was due to ingestion by the 

 weevil while drinking." He found that "only a very light mortality 

 would result from tests where the plants were kept absolutely dry after 

 poisoning ; but as soon as moisture was introduced the mortality increas- 

 ed greatly." 



During the simuner of 1919 Wilm.on Newell and Eli K. Bynum of the 

 Florida State Plant Board carried out a series of experiments testing 

 out the relation of dew or rain to the effective use of arsenates for 

 poisoning the boll weevil.^ Newell and Bynum carried out field cage 



^Journal of Economic Entomology, February 1920. 



