SUMMARY AND CONCLUSIONS. 95 



SUMMARY AND CONCLUSIONS. 



Hibernation is tlie term used to designate those phases in the life 

 and seasonal history of the boll weevil (or of any other animal or 

 plant) which are concerned with its existence through the winter and 

 the manner in which the species is protected or maintained in passing 

 from one season to the next. Food, climatic, and shelter conditions 

 are the principal factors concerned in hibernation. 



Food conditions in the fall govern largely the abundance of indi- 

 viduals which may enter hibernation and therefore affect the abun- 

 dance of the species in the following spring, since climatic and shelter 

 conditions govern largely the proportion of the hibernating individ- 

 uals which may survive. 



A large majority of the weevils developed in a field during the 

 season are produced from squares. 



Weevils becoming adult comparatively late in the season are more 

 likely to survive hibernation than are those which have been active 

 for a number of weeks before the time arrived for them to hibernate 

 successfully. 



It is possible that offspring of each of the four or five generations 

 which are produced on the average may survive to enter hibernation. 



No ''top crop" can reasonably be expected within the weevil- 

 infested area. 



All stages of the weevil may enter hibernation and under excep- 

 tionally favorable climatic conditions larvae which are more than half 

 grown may complete their development if in bolls and become mature 

 during the hibernation period. Immature stages in squares rarely 

 survive. Nearly all of the weevils surviving were adult before the 

 beginning of the hibernation period. 



The destruction of stalks in the fall, as long as possible before the 

 normal hibernation time, is the most economical and effective method 

 known for reducing the number of weevils entering hibernation. 



' ' Entrance into hibernation ' ' denotes the beginning of the generally 

 inactive period, but it does not necessarily imply a change of position 

 for the individuals involved. For the species and often also for the 

 individual it is a gradual process depending primarily upon tempera- 

 ture conditions. The duration of the entrance period for the species 

 depends upon the severity of the drop in temperature below about 

 43 degrees of mean average temperature. This period usually occurs 

 coincidently with the first killing frosts and extends through a period 

 of about twenty-five days. 



From close examination of 1,750 weevils it seems that about 60 

 per cent of those entering hibernation are males. 



The number of weevils per acre or per plant which may enter hiber- 

 nation depends especially upon preceding climatic and food conditions 



