HIBERNATION. 101 



Attention has already been called to the fact that many stages 

 enter the period of hibernation in an immature condition in unopened 

 bolls. That adult weevils hibernate entirely within the protection 

 afforded by the bracts and hulls of bolls has been abundantly demon- 

 strated. Messrs. Hinds and Yothers 1 showed, however, that the 

 percentage of live stages in bolls decreased rapidly during the winter, 

 thus proving that the bolls do not furnish perfect hibernation shelter. 

 Their results may be summarized as follows : 



Table XXXVI. — Seasonal decrease of live stages of the boll weevil in bolls; percentage 

 of bolls containing live stages. 



December 36. 00 



January 1. 15 



February 0. 29 



March 0. 00 



As would be expected, it was found that there was a greater per- 

 centage of survival in bolls in southern localities. 



During an ordinary season it can not be doubted that a large 

 majority of the weevils which survive find some other shelter than 

 the bolls hanging upon the plants. It is not, however, as easy a 

 matter to find weevils in rubbish scattered upon the ground as in 

 bolls. It is necessary to collect the rubbish very carefully and sift 

 it over cloth or paper to separate the weevils from the trash. In 

 this way it has been found that weevils hibernate extensively in the 

 leaf and grass rubbish distributed throughout the field. Naturally, 

 the cleaner the field in the fall the smaller will be their chances of 

 finding favorable shelter during the winter. 2 (PL XII, b.) 



Standing trees are a common sight in cotton fields, and while the 

 records of weevils found hibernating under bark are but few, they 

 are sufficient to indicate that these trees may be rather important 

 factors where they occur in considerable numbers. (PL XII, a.) 



Where the Spanish moss (Tillandsia usneoides) occurs, as in the 

 bottom lands in the coast section of Texas and in the southern por- 

 tions of the Gulf States generally, weevils find exceptionally favor- 

 able shelter. Many examinations of large quantities of moss have 

 been made to ascertain the importance of this form of shelter. The 

 maximum number of weevils per ton of moss is recorded by Messrs. 

 Newell and Dougherty (1909) as 3,158 in moss collected from an 

 elm tree located in a swamp at Mansura, La., December 23, 1908. 

 The moss was at a height or 15 feet. The tree was one-fourth of a 

 mile from the nearest cotton field. On January 9, 1910, Mr. C. E. 

 Hood found at Mansura 924 boll weevils and 2,156 boll- weevil para- 

 sites per ton of moss collected at from 1 to 8 feet above the ground. 

 The weevils seem to prefer the festoons of green-hanging moss to 

 the dead masses. (See Pis. XI, XIII.) 



Cornfields adjoining cotton, or cornstalks scattered throughout 

 cotton fields may shelter many weevils. This was first noticed by 

 Mr. E. A. Schwarz at Victoria, Tex., in the winter of 1901-2, and 

 has since been corroborated by a number of observers. Several 

 examinations have been made of haystacks in the vicinity of cotton. 



!Bull. 77, Bureau of Entomology. 



2 This paragraph and the remainder of the discussion in the present section is modified from Bull. 77, 

 Bureau of Entomology, pp. 30-33, 41, 42. 



