73 

 DEVELOPMENT. 



PERCENTAGE OF WEEVILS DEVELOPED FROM INFESTED 



SQUARES. 



During the season of 1902 part of the many squares gathered in 

 infested fields for the breeding of weevils were followed to learn some- 

 thing of the percentage which produced normal adults. No exami- 

 nation was made for those not yielding a weevil. The decay of the 

 square during the period from its falling to the maximum time that 

 must be allowed for weevils to escape normally so obliterates any 

 small amount of work by a larva that it is difficult even with exami- 

 nation to determine accurately the number of dead small larvae. 



Table XVIII. — Percentage of weevils from infested squares. 



Locality. 



Approximate date. 



Number 



of 

 squares. 



Number 



of 

 weevils. 



Percent- 

 age of 

 squares 

 producing 

 weevils. 





1902. 

 July to August. 



1,125 



387 



331 

 873 

 368 



360 

 108 



106 

 355 

 192 



32.0 



Guadalupe, Tex 



28.0 



1903. 



32.0 



Do . 



June to August 



August to September 



41.0 



Do 



52.0 







Total. . - 



3,087 



1,121 



36.3 









It seems safe to conclude that throughout the season fully one-third 

 of the squares which fall after receiving weevil injury may be expected 

 to produce weevils. 



DEVELOPMENT OF WEEVILS IN SQUARES WHICH NEVER FALL. 



It is generally true that squares seriously injured by the weevil 

 sooner or later fall to the ground. Some plants, however, shed the 

 injured squares more readily than do others. It seems to be a mat- 

 ter of individual variation rather than a varietal character. Thus 

 occasional plants retain a large proportion of their infested squares, 

 which hang by the very tip of the base of the stem. Normally the 

 squares are shed because of the formation of an absciss layer of corky 

 tissue across their junction with the stem. In the case of the squares 

 which remain hanging the formation of this layer seems to be incom- 

 plete, or else it becomes formed in an unusual plane, so that while the 

 square is effectually cut off, it merely falls over and hangs by a bit of 

 bark at its tip (PI. XII, fig. 47). In this position it dries thoroughly 

 and becomes of a dark-brown color. Plants showing 6 or 8 of these 

 dried brown squares are quite common in infested fields. Although 

 exposed to complete drying and the direct rays of the sun, the larvae 

 within are not all destroyed. This peculiarity reminds one strongly 

 of the European Anihonomus pomorum the work of which in caus- 



