Sabadilla dusts had practically no effect on cotton aphids, cotton leafworms, 

 bollworms, and boll weevils. Undiluted Ryania at 32 lbs. per acre was only mod- 

 erately effective against boll weevils. Five percent hexaethyl tetraphosphate 

 dusts were ineffective against boll weevils. A 25% azobenzene dust was nontoxic 

 or only slightly toxic to boll weevils. Two dust compositions, one containing 0.5% 

 of "piperonyl cyclohexenone" and 0.04% of pyrethrins in an unknown carrier, and 

 the other containing 0.0125% of piperonyl butoxide and 0.001% of pyrethrins in 

 pyrophyllite were not effective against boll weevils. 



1947 - Ivy, E. E., C. R. Parencia, Jr., and K. P. Ewing. A chlorinated camphene for 

 control of cotton insects. J. Econ. Ent. 40(4):513-5 17. 



In cage tests, a dust containing 20% of chlorinated camphene, applied at the 

 rate of 8 lbs. per acre, controlled the boll weevil, as well as did calcium arsenate 

 or benzene hexachloride. 



In field-plot experiments a dust containing 20% of chlorinated camphene gave 

 adequate control of comparatively heavy infestation of bollworms, boll weevils, 

 cotton aphids, and leafworms. The chlorinated camphene controlled the boll weevil 

 about as well as calcium arsenate and was slightly superior to calcium arsenate 

 in controlling the bollworm. 



A mixture of 5% of DDT and benzene hexachloride containing 2.88 or 4.5% of 

 the gamma isomer appeared to be slightly superior to chlorinated camphene 

 against the bollworm, but about equal against the boll weevil, aphid, and leaf- 

 worm. In a small-plot experiment (latin-square design) the yields were signifi- 

 cantly higher from the chlorinated camphene and from the DDT -benzene hexa- 

 chloride mixture than from the calcium arsenate. 



1947 - Kulash, Walter M. Benzene hexachloride and chlordane to control cotton boll 

 weevil. J. Econ. Ent. 40(5) :644-650. 



Benzene hexachloride dust, 5% gamma isomer content, was used in 6 repli- 

 cated plots for the control of the cotton boll weevil under field conditions in the 

 vicinity of Raleigh, North Carolina. Each plot consisted of 4 rows of cotton, 900 

 feet long. Plots were treated 5 times in the period from July 12 to August 14, 

 1946. In the July 12 and July 27 treatments, 1% gamma benzene hexachloride 

 dust was used, but it did not check the abundance of the second brood weevils 

 emerging at that time. The 3 other dust applications were made with dust con- 

 taining 5% of the gamma isomer, and these later applications reduced the infes- 

 tation of weevils considerably. 



In the field, the 5% dust did not seem to have any marked residual effect on, 

 weevils 3 or 4 days after application. The 5% dust, if used too heavily, burned 

 foliage. 



In the laboratory, nearly 3,000 weevils were tested with various concentra- 

 tions of benzene hexachloride dust, as well as chlordane dusts and sprays, 

 according to 2 different methods of testing. Benzene hexachloride dusts of 1%, 

 2%, 5%, and 10% gamma isomer content did not show any marked difference in 

 the number of weevils killed at 24 to 72 hours after treatment when the weevils 

 were merely exposed to the dust and did not come in contact with it. According to 

 the second method of testing, weevils were allowed to come in contact with the 

 test materials immediately after they had been applied to freshly cut sprigs of 

 cotton foliage. Up to 8 hours after exposure this method produced a more rapid 

 knock-down and mortality at all concentrations than did the first method of test- 

 ing, in which the weevils did not come in contact with the test materials. 



Tests with benzene hexachloride dusts exposed to room air for 3 days before 

 the introduction of the weevils (according to the first methods of treatment) 

 showed that there was a marked reduction in the effectiveness of the dust at all 

 4 concentrations used. 



Chlordane in dust and spray form was also used according to the 2 different 

 methods of testing. Liquid formulations of chlordane were apparently more toxic 

 to boll weevils than were dust formulations of the same material but the former 

 did not produce as rapid a mortality as did the dusts. 



Benzene hexachloride dusts, 2% and 5% gamma isomer content, were more 

 toxic to boll weevils than chlordane dusts of 2% and 5% concentrations. 



42 



