8 BULLETIN" 344, U. S. DEPARTMENT OF AGEICULTUEE. 



With the existing variations in time of emergence it is impossible 

 to determine the exact number of generations per year, but most of 

 the weevils seem to have only one or two, the last remaining in the 

 pupal cells in the bolls and so hibernating. 



The activity of the weevils seems to continue until stopped by the 

 cold weather. It was greatly decreased in most places through 

 October, but a few weevils were still active on the 1st of November. 



EMERGENCE OF WEEVILS. 



The study of the weevil activity in nature was greatly confused by 

 the extreme variation in the time of emergence from hibernation. 

 These weevils pass the winter in pupal cells in the Thurberia boll and, 

 instead of emerging in the spring with the first warm weather, pro- 

 long the dormant period far into the season before leaving the cell. 

 In fact, some individuals have been found in old cells as late as the 

 1st of September, though nearly all emerge during July and August. 

 Because of the possible economic importance of this delayed emer- 

 gence in relation to the transfer of the weevil from Thurberia to cot- 

 ton, cage tests were conducted and careful observations made in the 

 field to determine under what conditions the weevils will emerge. 



For the cage tests a number of infested Thurberia bolls which had 

 remained hanging on the plants since the fall of 1913 were collected 

 in the upper part of Soldiers Canyon on June 6 and were kept in a 

 dry box until the time of starting the tests. 



The treatment of the different lots of infested bolls was as follows: 



No. 1. Bolls not moistened placed in empty tumbler in shade. 



No. 2. Bolls not moistened placed in empty tumbler in sun. 



No. 3. Bolls not moistened placed on moist sand in shade. 



No. 4. Bolls not moistened placed on moist sand in sun. 



No. 5. Bolls immersed in water 1| minutes and placed on moist sand in shade. 



No. 6. Bolls immersed in water 1J minutes and placed in empty tumbler in shade. 



No. 7. Bolls immersed in water 30 minutes and placed on moist sand in shade. 



No. 8. Bolls immersed in water 30 minutes and placed in dry tumbler in shade. 



No. 9. Bolls immersed in water 30 minutes and placed on moist sand in sun. 



These tests were started July 11, and each lot was examined at 

 frequent intervals until September 22 and all emergence noted. 

 Five bolls were placed in each lot. On September 22 all bolls were 

 opened and the condition of the weevils inhabiting them noted. 



From the unmoistened bolls placed in dry tumblers no weevils 

 emerged. When the unmoistened bolls were placed on moist sand 

 and left in the shade, two weevils emerged, but when they were 

 placed in the sun none emerged. When the bolls were immersed 

 in water for H minutes and then placed on moist sand in the shade 

 four emerged, but those moistened in the same manner and placed 

 in a dry tumbler in the shade produced none. When immersed in 

 water 30 minutes and left on moist sand in the tent three emerged 

 and those moistened in the same manner and placed on moist sand 



