

effectiveness of the fine cryolite and made it comparable to calcium arsenate. 

 Nicotine compounds gave very little or no control. There was no significant dif- 

 ference between calcium arsenate and the mixture of calcium arsenate and cal- 

 cium carbonate. 



From these studies and from general observations made throughout the 

 season, it appears that cryolite might be developed into a satisfactory substitute 

 for calcium arsenate in the control of A. grandis, provided that its dusting quali- 

 ties are good and that the percentage of sodium fluoaluminate is high. 



1939 - Smith, G. L., A. L. Scales, and R. C. Gaines. Additional records on the effec- 



tiveness of several insecticides against three cotton insects. J. Econ. Ent. 

 32(6):798-802. 



The New York method shows definite positive correlations between net boll 

 weevil mortality and the percentage of water-soluble AS2O5. Dose -mortality rec- 

 ords with fifth instar cotton leaf worms showed that smaller doses of calcium 

 arsenates were required if they contained a high percentage of water-soluble 

 AS2O5 than when they contained a low percentage, and the intermediate percent- 

 age fell between the high and low. Definite relations are also shown between the 

 percentage of water-soluble AS2O5 by the New York method and the net boll 

 weevil mortality with calcium arsenate fractions prepared by means of a centrif- 

 ugal air separator. Di-calcium arsenate was more effective against the boll 

 weevil than either basic calcium arsenate or a commercial calcium arsenate. 

 The addition of wetting agents to calcium arsenate, to derris, to derris -sulfur 

 mixture, to sulfur, and to cryolites, did not appear to affect significantly the 

 insect mortality resulting from use of these insecticides. 



1940 - Bondy, F. F., and C. F. Rainwater. Investigations on the control of cotton in- 



sects. S.C. Expt. Sta. 1939-40. Rpt. 53:121-127. Clemson, 



The development, since 1923, of work on the control of Anthonomus grandis 

 Boh. on cotton in South Carolina is briefly reviewed. Experiments during 1928-40 

 showed that the most effective and profitable treatment was dusting the cotton 

 with calcium arsenate at 5-day intervals after 10% of the squares became infested. 

 The chief objections to this treatment were that it is expensive and requires spe- 

 cial dusting apparatus, that it is often followed by infestation by leaf aphids ( Aphi s 

 gossypii Glov.), and that it may cause injury to subsequent crops. 



In South Carolina, however, no case of soil injury was observed during sev- 

 eral years of investigations. Tests in South Carolina and Mississippi to determine 

 the amounts of calcium arsenate that would cause injury on different types of soil 

 showed that 200 lbs. per acre on light sandy soils results in some injury to 

 cowpeas but that cotton is not damaged until 400 lbs. is applied. On heavier soils, 

 1,600 lbs. per acre caused no damage to cotton. Ordinarily, not more than 40 lbs. 

 of calcium arsenate per acre would be needed per year for weevil control, and it 

 was considered that the risk of consequent soil injury has been greatly exag- 

 gerated. 



1940 - Eddy, C. O. Insect pests and their control. La. Agr. Expt. Sta. B. 323, 51 p. 



Cryolite gave very little control of the boll weevil on cotton, but unlike cal- 

 cium arsenate, caused no injury to growing rice in the year following application 

 on cotton. 



1940 - Gaines, J. C. Tests of insecticides for certain cotton insects during 1939. J. 

 Econ. Ent. 33(4):684-688. 



Tests were made at College Station, Tex., in 1939 to obtain information on 

 the comparative effectiveness against the bollworm and boll weevil of a specially 

 prepared calcium arsenate, a commercial calcium arsenate, and a synthetic 

 cryolite. An infestation of the rapid plant bug that developed on one of the plots 

 made it possible to obtain some information on the action of the arsenicals on 

 this pest, also. 



The special calcium arsenate, containing large particles and a high percent- 

 age of water-soluble arsenic pentoxide, gave a significantly better control of the 



28 



