432 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 4 



STUDIES IN THE BIOLOGY OF THE BOLL WEEVIL IN 

 THE MISSISSIPPI DELTA REGION OF LOUISIANA' 



By R. A. CusHMAN, Bureau of Entomology, U. S. Department of Agriculture 



The information contained in the following pages was obtained 

 in a series of studies in the life history and biology of the boll weevil, 

 carried on by the writer at the Delta Boll Weevil Laboratory at 

 Tallulah, La. Owing to the fact that what work was accomplished 

 along these lines was done in what time could be spared from other 

 investigations, the methods employed were more or less crude and the 

 results obtained somewhat meager. However, the data obtained are 

 of considerable interest and very suggestive of opportunities for future 

 investigation along similar lines. 



The experiments were started with the idea of determining the max- 

 imum and minimum number of generations during a season, but as the 

 work progressed new Hnes of investigation presented themselves, and 

 several of these were studied to some extent. 



As no provision had been made to have cotton in the proper stage 

 at an early date and since the season was very backward, the begin- 

 ning of the work was unavoidably delayed until June 21, when squares 

 began to appear in the field. On account of the lack of time neces- 

 sary for carrying on the work in plant cages, it was necessary to utilize 

 picked squares and cages of various sorts. This introduced the first 

 unnatural condition. In nature, an infested square stays on the plant 

 six or seven days after being punctured, during which time it grows and 

 retains its moisture to a large extent. Under the conditions as im- 

 posed in the experiments the squares began drying before being 

 infested. This had the effect of hmiting the food supply of the devel- 

 oping larvae, and caused a large percentage of the weevils reared to 

 be small, poorly developed individuals. This was not particularly 

 noticeable during the hotter weather, when the developmental period 

 was of short duration; but late in the season, when the developmental 

 period was some days longer, it became such a serious matter that very 

 few weevils were reared, and the work had to be concluded before 

 breeding in the field had ceased. This difficulty was increased by the 

 necessity of importing squares from Texas during September and Octo- 

 ber, owing to the practically total infestation at Tallulah. The fail- 

 ure to determine the point originally intended was due to this factor. 



Throughout the work the squares either dried or rotted badly, 

 according as they were placed after infestation in well ventilated or 



1 Published by permission of the Chief of the Bureau of Entomology. 



