103 



probabilit}^ that, in the southern part of the State at least, man}" of 

 them live and mature, emerging in the spring. It may be that this 

 gradual maturity of the hibernated weevils is one of the reasons why 

 the}' emerge so irregularly from their winter quarters. 



SEASONAL HISTORY. 

 HIBERNATION. 



ENTRANCE INTO HIBERNATION. 



Not all weevils go into hibernation at the same time, but as the mean 

 average temperature falls to between 55° and 60° F. they gradually 

 cease feeding, and, numbed and sluggish, they crawl into almost any 

 place which furnishes them some measure of protection from the cold. 



Even after frosts have blackened the foliage and squares and entirely 

 checked the growth of the plant, some weevils can be found moving 

 in a cotton field upon warm days. Weevils which are old and nearly 

 exhausted die as the cold weather comes on. Their vitality has been 

 expended in other ways and they do not survive the winter. Many of 

 those which are still vigorous and strong will continue to feed a little, 

 and females will occasionally deposit eggs so long as cotton remains 

 green. 



Temperature and available food supply seem to be the most impor- 

 tant ^actors in determining the time of hibernation. In general, it 

 may be said that many weevils are active so long as their food con- 

 tinues in fit condition to sustain them. Some, however, undoubtedly 

 seek shelter before frosts occur. From numerous observations made 

 in the laboratory, it appears that weevils will starve when deprived of 

 cotton if the mean average temperature continues long above a point 

 somewhere between 60° and 65° F. As the mean average falls below 

 60°, hibernation may take place successfully. 



In determining the latest date at which the stalks may be destroyed 

 and still accomplish as great destruction of the weevils as is possible, 

 it is important that we should know approximately the time at which 

 weevils begin to go into hibernation. Naturally, this time w^ill vary 

 considerably between the northern and southern portions of the State, 

 the variation being parallel with the fall in temperature. Terrell, 

 Tex., was one of the northernmost localities available for observations 

 in 1904. Unfortunately conditions at this point were so modified by 

 defoliation of the cotton by the leaf worm in October as to interfere 

 considerably with the normal action of the weevils. In portions of 

 the fields which remained green most weevils disappeared during the 

 latter part of October and the first of November. Throughout Novem- 

 ber a few weevils still remained active, and occasionally upon warm 

 days weevils emerged from infested bolls. 



