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Counties of Texas were found to fit logistic growth curves. Boll weevil numbers 

 Increased exponentially through July, Aug., and Sept. at rates up to ca. 2.70- 

 fold/wk in an untreated field compared to 1.7A-fold avg in insecticide treated 

 fields. During Oct. the population growth rate slowed and finally reached zero. 

 The relation between the mean number of squares available to each weevil and 

 percentage of weevil damaged squares fit a curvilinear model. This model can 

 be used to provide an estimate of the number of adult weevils per ha based on 

 Z damaged squares and an estimate of the number of squares per ha. Conversely, 

 numbers of damaged squares can be estimated based on numbers of adult weevils. 



852. ; Adklsson, P. L.; and Rummel, D. R. 1967. Effects of the diapause 

 boll weevil control program on the size and rate of increase of boll 

 weevil populations in the High Plains of Texas. Tex. Agric. Exp. Stn., 

 Dep. Entomol. Rep. 7, 11 pp. 

 Effects of the current diapause boll weevil control program on the size and rate 

 of increase of boll weevil populations in the High and Rolling Plains during 1966 

 were studied in fields which had been treated with ultra-low-volume applications 

 of malathion during the fall months of 1964, 1965 and 1966. The size of the 

 population in these fields were compared to that of one in a field which was 

 never treated with insecticides. Results showed that the populations were 

 extemely small in both treated and untreated fields until early September. 

 During September and October, the estimated number of weevils in the untreated 

 field increased almost 90-fold, increasing from 399 to more than 35,000 adults 

 per acre. In contrast, the populations in the treated fields were held stable 

 during the fall months at relatively small numbers per acre. The difference 

 in the size of the two populations show the effectiveness of the present dia- 

 pause boll weevil control program in reducing populations. However, the rate 

 of increase of the population in the untreated field Indicate tliat if the pre- 

 sent control efforts were discontinued that the boll weevil has the reproductive 



