allowed to feed for varying lengths of time on squares, blooms, or bolls, Fat 

 determinations were made by extracting the fat in Soxhlet apparatus with ethyl 

 ether. 



1959 - Brazzel, J. R., and L.D. Newsom. Diapause in Anthonomus grandis, Boh. J. Econ. 

 Ent. 52(4):603-6ll. 



Part of the boll weevil population enters diapause late in summer and early 

 in fall in La. Winter is passed in this condition. Diapause in this insect is 

 characterized by cessation of gametogenesis and atrophy of gonads, increase 

 in fat content, decrease in water content, and decrease in respiratory rate. 



Diapausing boll weevils were found in ground trash each month of the year 

 except June and July. It is almost certain that they were also present there 

 during these 2 months but no collections of ground trash were made at this time. 

 Diapause occurred in some individuals as early as July 30, and movement to 

 winter quarters began prior to August 16 during 1957. 



Fat and water content remained relatively stable in diapausing weevils during 

 late fall, winter, and early spring. There was a sharp decrease in fat and a 

 corresponding increase in water content soon after they moved back to cotton in 

 the spring. 



Males were able to resume spermatogenesis prior to leaving their winter 

 quarters but oogenesis did not begin until the females had fed on seedling cotton. 



1959 - Brazzel, J. R. The effect of late-season applications of insecticides on 



diapausing boll weevils. J. Econ. Ent. 52(6): 1042- 1045. 



Three insecticides were applied to cotton plants from August 22 through 

 November 20, after the normal control program was completed, to determine 

 the effect on diapausing boll weevil populations under caged conditions. Deter- 

 mination by dissection indicated relatively large numbers of weevils diapaused 

 in the toxaphene and calcium arsenate treatments but only 1 diapaused in the 

 plots treated with methyl parathion. These results indicated that properly timed 

 late season insecticide applications, coordinated with cultural practices, may 

 be effective in reduction of the overwintering boll weevil population. 



1960 - Brazzel, J. R., and B. G. Hightower. A seasonal study of diapause, reproductive 



activity, and seasonal tolerance to insecticides in the boll weevil. J. Econ. Ent. 

 53(l):41-46. 



A seasonal study of reproductive activity, incidence of diapause and seasonal 

 tolerance to toxaphene and Guthion (O, O-dimethyl S-(4-oxo-3H- 1,2,3, -benzo- 

 triazine-3-methyl) phosphorodithioate) in the boll weevil was conducted in 4 

 cotton fields in central Texas. Diapausing weevils were first found in the various 

 fields from late July through August. Once diapausing weevils were found in a 

 field, they occurred in all subsequent collections from the field. 



Reproductive activity was high from June until the onset of diapause. One 

 peak of reproductive activity occurred in September on regrowth cotton. Over- 

 wintered weevils that emerged early in the season with fat content over 10% of 

 the dry weight were harder to kill with toxaphene than weevils of the current 

 season collected during June and early July. Seasonal tolerance to toxaphene of 

 up to 100-fold occurred with the onset of diapause in the populations. No evidence 

 of seasonal tolerance to Guthion was found. 



PHYSIOLOGY AND MORPHOLOGY 



1916 - Blatchley, W. S., and C. W. Leng. Rhynchophora or weevils of northeastern 

 America, p. 294. The Nature Publishing Co., Indianapolis, Ind. 

 Contains a description of an adult Anthonomus grandis . 



1926 - Walker, H. W., and J. E. Mills. Progress report of work of the Chemical 

 Warfare Service on the boll weevil. J. Econ. Ent. 19(4):600-601 . 



The average weight of a boll weevil is reported to be 16 milligrams. 



149 



