INSECTS INJURIOUS TO COTTON 



267 



during the winter, and the adult weevils soon go into hibernation. 

 When seeking places for hibernation the weevils migrate from 

 field to field, and it is at this season that the principal migration 

 of the pest takes place. The weevils may hibernate in hedges, 

 woods, corn-fields, haystacks, or farm buildings, particularly 

 about seed-houses or similar situations. Experiments have 

 shown that Spanish moss forms an exceedingly favorable place 

 for hibernation, and that many weevils pass the winter in it on 

 trees some distance above the ground. Others may hiber- 

 nate in the cotton-field, crawling into cracks, under grass, 

 weeds, and trash, and into the 

 empty cotton burrs, while in 

 the more southern sections 

 many hibernate in injured 

 bolls. The weevils which 

 hibernate most successfully 

 do so outside of the cotton - 

 fields. The number which 

 survive the winter has been 

 accurately determined under 

 various conditions for several 

 seasons, and depends upon 

 the minimum temperature, 

 the amount of moisture, and 

 the kind of shelter. Thus in 

 central Texas but 2 or 3 per 



cent survive in many normal winters, while in the open winter of 

 1906-07 11.5 per cent survived; in south Texas 15 per cent may 

 survive, and in experiments made in Central Louisiana in 1908- 

 09 with rather favorable conditions 20 per cent survived. The 

 importance of reducing the number whicn survive the winter is 

 evident. 



Natural Control. If infested squares fall to the ground and lie 

 on the unshaded, hot soil the larvae or pupse within them are soon 

 killed. As many as 40 per cent of the immature stages have thus 

 been found dead in many fields. The importance of wide rows 



P'IG. 197. Cotton boll weevils hiber- 

 nating in locks of cotton removed 

 from old bolls left on stalks over 

 winter. 



