44 BULLETIN 926, U. S. DEPARTMENT OF AGRICULTURE. 



The average period from oviposition to adult of all weevils bred 

 under insectary conditions on upland cotton squares was 14.91 days. 

 On sea-island cotton the average period from egg to adult for all 

 weevils bred under insectary conditions was 14.94 days. 



The field-bred weevils showed more vitality than weevils bred 

 under artificial conditions. 



Under field conditions the average length of time the infested 

 squares hung on the upland cotton plants after egg puncture was 11.5 

 days. The time required to complete the development of the im- 

 mature weevil after the infested square dropped to the ground was 

 10.8 days in upland cotton squares. 



There was practically no difference shown in the length of the 

 developmental period of the boll weevils bred in short-staple upland, 

 long-staple upland, and sea-island cotton squares. 



The developmental period of the boll weevil was approximately 

 7.5 days longer under field conditions than under insectary condi- 

 tions at Madison, Fla. 



Soil temperatures of 120° F. and higher are usually fatal to the im- 

 mature weevils under field conditions. 



The boll weevil at Madison, Fla., shows a decided tendency to 

 form a new variety. 



The hibernation of the weevil at Madison, Fla., is incomplete and 

 the adults are seldom inactive more than 30 days at a time. 



The emergence from hibernation of the weevil in Florida is very 

 gradual, the total daily emergence bearing a direct relation to the 

 total daily rainfall. 



Weevils survived the winter in larger numbers in cages set on 

 the ground in the woods than in the open field or in cages in trees 

 10 feet above ground. Weevils placed in hibernation cages on 

 November 15 survived in larger numbers than on any other date 

 of installation. 



The percentage of total emergence from hibernation begins with 

 more acceleration in Florida than in Texas up to the time that 25 

 per cent emerges. After 25 per cent of the weevils have emerged in 

 Florida the emergence is less rapid and the Florida emergence curve 

 very closely approaches the emergence curve for Louisiana. 



The total percentage of hibernating weevils that survived the 

 winter of 1918-19 at Madison, Fla., was 7.54. 



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