Regular applications of insecticides were necessary to keep heavy infestations 

 under control late in the season. Where they were so applied, control was excel- 

 lent and migration was prevented almost completely. 



Timing applications by presence of feeding punctures and live weevils held 

 infestations at low levels without wasting insecticides. 



1951 - Rainwater, C. F., and J. C. Gaines. Seasonal decline in the effectiveness of cer- 

 tain insecticides against boll weevil. J. Econ. Ent. 44(6):971 -974. 



Field cage tests conducted at College Station, Tex., over a 3-year period 

 verify the observed fact that certain insecticides are less effective against the 

 boll weevil late in the season than they are earlier. In general, toxaphene, 

 benzene hexachloride, aldrin, and dieldrin were approximately 50% as effective 

 in October as in July, whereas undiluted calcium arsenate was approximately 

 67% as effective. The period of greatest reduction in effectiveness occurred in 

 September and October, as contrasted with the effectiveness of June and July. 



Toxaphene was consistently less effective month by month from June to 

 September, inclusive, for each of the 3 years. Increased concentrations and 

 increased dosages up to 4 times the normal rate of application did not significantly 

 affect the percent kill of late- season boll weevils. Additional tests showed that it 

 required 240 times aa much toxaphene to kill the same percentage of boll weevils 

 in October as in July, and that all the other insecticides tested required ex- 

 tremely high dosages to effect kill in October comparable to that obtained in July. 



In tests designed to determine comparative residual effectiveness, aldrin and 

 benzene hexachloride lost considerably more than 50% of their effectiveness within 

 1 day, whereas heptachlor, dieldrin, and toxaphene lost 39%, 32%, and 45%, 

 respectively. Calcium arsenate lost none of its effectiveness in 1 day, and EPN 

 lost only 2%. After 5 days the chlorinated hydrocarbon insecticides were virtually 

 ineffective. 



1951 - Reed, John K., and M. D. Farrar. Bio-assay of cotton dusts with adult boll 

 weevil. J. Econ. Ent. 44(6): 1 01 3- 1 014. 



Appropriate averages from 420 samples of commercial dusts tested on boll 

 weevils under laboratory conditions show (1) the use of sulfur as a diluent in cot- 

 ton dusts added little or nothing to the kill of adult boll weevils; (2) 20% toxaphene 

 dusts gave a higher rate of kill and killed faster than 3-5 benzene hexachloride- 

 DDT in the laboratory. 



A 3-5-0 benzene hexachloride-DDT dust mixed by grinding killed boll weevils 

 quicker and required less dust for equal mortality than a similar dust in which 

 the insecticide was impregnated on a carrier. 



1951 - Smith, W. R., and S. L. Calhoun. Spraying for early-season control of boll weevil. 



J. Econ. Ent. 44(6):9l 9-920. 



Tests were conducted in 9 fields on 5 southern Mississippi Delta plantations 

 in 1949 to determine the efficiency of toxaphene applied as a spray by tractor- 

 mounted equipment for early- season control of the boll weevil. The cost of ap- 

 plication and the feasibility of incorporating cotton insect control with regular 

 cultivation were also investigated. 



Sprays could be applied efficiently in the course of cultivation, and the ap- 

 plication of toxaphene during the prebloom and early-bloom stages of cotton 

 development delayed by 19 days the date when 25% of the squares became in- 

 fested. 



A significant difference in seed-cotton yield was observed in 6 of the 9 

 treated fields. Climatic conditions reduced the effectiveness of regular seasonal 

 applications of poison, and poor control of the boll weevil was obtained in most 

 fields. 



1952 - Fife, L. C, Floyd F. Bondy, and R. L. Walker, Jr. Spray versus dust for boll 



weevil control with ground equipment. J. Econ. Ent. 45(l):l6-19. 



Spray and dust formulations of chlordane plus DDT, toxaphene plus DDT, 

 benzene hexachloride plus DDT, toxaphene, dieldrin, and aldrin were tested in 

 large field plots for boll weevil control during 1949, at Florence, South Carolina. 



57 



