ENTRANCE INTO HIBEENATION. 13 



period individuals may exist which represent an advance of only 

 one generation. During the entire season the average period required 

 for development, in squares, from the deposition of the egg to the 

 emergence of the adult weevil is from 18 to 20 days. In bolls the 

 developmental period may exceed 60 days. The average period 

 during which each female may deposit eggs is between 50 and 60^ 

 days. The average number of eggs which each female msij be 

 expected to deposit is not far from 100. The average period required 

 for each generation is between 40 and 45 days. In southern Texas, 

 therefore, five full generations of the w^eevil may usually be expected, 

 and owing to the somewhat shorter season and lower temperatures 

 occurring in northern Texas four generations is prol)ably the true 

 average in that section of the vState. There is no particular hiber- 

 nation brood, but representatives of all generations may survive 

 and enter hibernation. From these considerations it will be readily 

 understood that during the latter part of the season the multiplica- 

 tion is primarily dependent upon the food supply, and that the com- 

 mon practice of allowing stalks to stand after the crop becomes 

 matured is primarily responsible for a large proportion of the weevils 

 which may enter hibernation. 



It is but repeating statements which have been frequently made 

 in former publications of this investigation to say that the vain 

 hope of securing some top crop of cotton, in case there should be a 

 late fall, is probably the principal reason which has been urged for 

 allowing this growth of the plant. So far as we know there is no 

 record of a top crop ever having been secured in a field which had 

 become thoroughly infested with boll weevils earlier in the season. 

 Wliile it is true that in uninfested regions some top crop has occa- 

 sionally been formed and may occasionally be secured in the future, 

 it is not putting the facts too strongly to say that within the weevil- 

 infested area this has never occurred and should never be expected. 



STAGES ENTERING HIBERNATION. 



The reproductive activity of the weevil continues steadily until 

 the plants are destroyed by frost. It gradually decreases coinci- 

 dently with the gradual decrease in heat. All stages from the egg 

 to the adult may be found in both squares and bolls, even after frosts 

 have occurred. The immature stages in squares are not immediately 

 killed unless the freeze is exceptionally severe, but probably very 

 few of these survive to reach maturity and to emerge during the 

 following spring. Only those which are nearly adult at the time 

 frost occurs may be expected to emerge. These might emerge upon 

 warm days following the colder weather, but in the absence of a 

 fresh food supply would soon die. In the fall of 1903 Prof. E. D. 

 Sanderson records, from an examination of 700 squares at the middle 



