treated with DDT alone. Poor recovery of 

 the applied DDT was obtained. Tests with C 14 

 labeled DDT indicated that the treated weevils 

 rubbed off much of the toxicant and converted 

 a small quantity to a compound that did not 

 respond to the colorimetric analysis used. 



Resistant weevils treated with toxaphene 

 absorbed less than similarly treated suscepti- 

 ble weevils. 



107. Lindquist, D. A., and others. Labora- 

 tory studies on sterilization of the boll weevil 

 with apholate. Jour. Econ. Ent. 57: 745-750. 

 1965. 



L. J. Gorzycki, M. S. Mayer, A. L. Scales, 

 and T. B. Davich, joint authors. 



Male boll weevils can be sterilized with 



I apholate. Treatment methods that resulted in 

 at least partial sterility were: (1) Dipping the 

 male weevil in aqueous apholate solutions, 

 (2) feeding apholate to the weevils, (3) expo- 

 sure to apholate residues on glass, and (4) top- 

 ical application. Apholate was toxic to boll 

 weevils and effective sterilizing dosages re- 

 sulted in high mortalities. However, treated 

 male weevils often regained fertility in 10 to 

 20 days after treatment. Egg hatch was not 

 a good criterion for estimating sterility, since 

 data indicated that apholate treatment pro- 

 duced a type of dominate lethal that was ex- 

 pressed in the newly hatched larvae. 



108. Lindquist, D. A., and others. Sys- 

 temic activity of dimethoate applied to cotton 

 seeds. Jour. Econ. Ent. 54: 1132-1135. 1961. 



J. Hacskaylo, J. C. Clark, and T. B. Davich, 

 joint authors. 



Dimethoate was not exceptionally effective 

 as a systemic cottonseed treatment against the 

 boll weevil and cotton aphid. Applied as a seed 

 treatment it caused considerable reduction in 

 seedling emergence. 



P 32 labeled dimethoate applied as a cotton- 

 seed treatment was most rapidly absorbed 1 

 to 3 days after planting. It did not reduce the 

 total emergence of artificially deteriorated 

 seed, but it did reduce the rate of emergence 

 somewhat. Seeds deteriorated for 2 days ab- 

 sorbed more dimethoate than seeds deterio- 

 rated for 0, 1, 3, or 4 days. 



Dimethoate was less toxic than phorate to 

 boll weevil larvae and adults. 



109. Lloyd, E. P., Laster, M. L., and 

 Merkl, M. E. A field study of diapause, dia- 

 pause control, and population dynamics of the 

 boll weevil. Jour. Econ. Ent. 57: 433-436. 

 1964. 



In 1960-61, 1-year tests were conducted in 

 three cottonfields in Mississippi to study the 

 relation between plant fruiting and the first 

 entry of boll weevils into diapause. Tests were 

 set up to evaluate the effectiveness of methyl 

 parathion in controlling diapausing weevils 

 and to measure population increases on dry- 



land cotton. In the diapause studies first 

 diapausing weevils appeared in all three fields 

 at cessation of flowering, when only bolls re- 

 mained as the food source. In the diapause- 

 control studies, seven applications of 'methyl 

 parathion spray applied at one half pound per 

 acre greatly reduced the overwintering popu- 

 lation, but they did not eliminate it. In the 

 limited studies of population dynamics, sea- 

 sonal generation-to-generation increases aver- 

 aged fivefold and ranged from onefold to 9.6- 

 fold. 



110. Lloyd, E. P., McMeans, J. L., and 

 Merkl, M. E. Preferred feeding and egg lay- 

 ing sites of the boll weevil and the effect of 

 weevil damage on the cotton plant. Jour. Econ. 

 Ent. 54: 979-984. 1961. 



Females damaged fruit of the cotton plant 

 more than did the males. Preferred feeding and 

 egg-laying sites were the squares on the upper 

 half of the plants when the population was low. 

 As the population increased, small bolls were 

 damaged as well as squares; the damage was 

 intensified on the upper part of the plants and 

 reached into the lower fruiting branches. Bolls 

 1 to 19 days old were damaged. 



Exposure of the cotton plant to feeding and 

 egg-laying for 4 or 5 days resulted initially in 

 increased square abcission and slightly reduced 

 boll abcission. No difference occurred in total 

 boll set for the entire season between the test 

 and the check plants. 



111. Lloyd, E. P., and Merkl, M. E. Sea- 

 sonal occurrence of diapause in the boll weevil 

 in Mississippi. Jour. Econ. Ent. 54: 1214- 

 1216. 1961. 



In the one field studied in 1958 dispause oc- 

 curred by August 26. In the seven fields studied 

 in 1959 it was observed as early as August 11 

 and as late as September 8. Weevil populations 

 generally entered diapause in two distinct pe- 

 riods. Gross observations indicated that entry 

 in the first period was related to the maturity 

 of the plants in the different fields. Adequate 

 food supply appeared to be necessary. 



Diapausing weevils were first recovered 

 from ground trash September 10, 1958, and 

 September 9, 1959, which indicated movement 

 of diapausing segments of the weevil popula- 

 tions to overwintering quarters well in advance 

 of the first killing frost. 



112. Lloyd, E. P., Merkl, M. E.. and Crowe, 

 G. B. Effect of boll weevil infestations on 

 yield and quality of cotton. Jour. Econ. Ent. 

 55: 225-227. 1962. 



The effect of four different levels of infesta- 

 tion by the boll weevil on earliness, yield, and 

 quality of cotton lint were evaluated in a rep- 

 licated field-cage experiment at Stoneville, 

 Miss., 1959-60. Seasonal square infestation 

 levels of about 0, 25, 50, and 75 percent were 

 used. As infestation levels increased plant fruit- 



17 



