30 BULLETIN 358, I T . S. DEPARTMENT OF AGRICULTURE. 



Here it is seen that the weevils reared from squares averaged 15 

 days while those from bolls averaged 16.7 days. The comparative 

 percentages of eggs producing adults are also interesting. Of those 

 laid in squares, 12.1 per cent produced adults while 33.1 per cent 

 of those in bolls produced adults. This is undoubtedly due to the 

 fact that some of the squares were too small to feed the larvse to 

 maturity and also to the fact that when two or more eggs hatch in 

 the same square the shortage of food usually results fatally to both. 

 Tne greater deposition in the squares is very marked. 



EFFECT OF SIZE OF SQUARE ON WEEVIL DEVELOPMENT. 



In July, 1915, an experiment was conducted to determine the 

 effect of the size of the cotton square on the weevil developmental 

 period. An abundance of clean squares was placed in a large wire 

 cage with fertile females and left for one day. The squares con- 

 taining single eggs were separated into lots of 50 squares each; one 

 lot being small squares, one medium-sized, and the third large. The 

 small squares produced one weevil in 14 days, the medium-sized 

 squares produced 20 weevils in an average of 14.1 days, and the 

 large squares produced 18 weevils in an average of 14.5 days. While 

 the number of weevils reared is too small to make the results con- 

 clusive, it seems that the length of the developmental period is 

 directly proportional to the amount of food available. This appears 

 quite probable in view of the fact that the developmental period is 

 always considerably longer in cotton bolls than in cotton squares. 

 The small squares seemed not to furnish sufficient food for the weevil 

 development as only one weevil was able to reach maturity in the 50 

 tested. 



GENERATIONS. 



One series of weevils was carried through the season of 1914 to 

 determine the maximum number of generations possible in cotton 

 squares in one year. For starting the series hibernated females were 

 collected immediately after emergence in the spring and placed with 

 males on cotton squares. The first eggs of these females were saved 

 and the progeny reared. The first adults to mature from these were 

 mated and their first eggs secured. This procedure was followed 

 through the season, and the results are shown in Table XXV. Be- 

 tween the first of June and the first of November these weevils were 

 carried through seven generations, the first and only weevil of the 

 seventh generation emerging November 1. This individual was very 

 weak and died in a few days, but as the cold weather at this time 

 had stopped all breeding in the field it was evident that the limit of 

 the breeding season had been reached. 





