NATURAL DISSEMINATION. 



85 



The status examinations upon which these maps were based show 

 the following average percentages of infestation in Texas. (See Table 

 XXXI.) 



Table XXXI. — Percentage of infestation by the boll weevil in Texas in August; years 



1906 to 1911. 



NATURAL DISSEMINATION. 



The natural movements of the boll weevil are of several more or less 

 distinct kinds. For several months in the spring there is a general 

 dispersal in search of food. After the cotton commences to square 

 there is a steady spread across the fields from the vicinity or the 

 places where the insects have hibernated. This may become a 

 spread from field to field. In late summer there is a sudden and 

 wide dispersal, which is shortly followed by a search for hibernation. 



SPRING SEARCH FOR COTTON. 



After a quiescent period of from five to eight months the weevils 

 leave their hibernation quarters and start in search for food. During 

 a warm period, such as was experienced in March, 1907, many weevils 

 come out of hibernation long before any cotton has made its appear- 

 ance. Without doubt these weevils wander considerable distances 

 and finally either die or reenter the quiescent state on account of 

 lower temperatures. As the emergence from hibernation covers a 

 period of about three months there is little or no regulation of the 

 direction of flight, such as might occur if all emerged at the same time 

 during a high wind. Elaborate tests have been made by releasing 

 marked weevils fresh from hibernation in the vicinity of cotton fields. 

 Invariably after careful search a very small percentage of these wee- 

 vils have been found in the nearest cotton. 



The experiments of Mr. A. C. Morgan in 1906 at Victoria, Tex., 

 give the most specific data on individual flight. Seven hundred and 

 eleven weevils were used in the experiments, of which 355 had been 

 fed and 356 were unfed. Of the fed weevils 179 were male and 176 

 female, while of the unfed weevils 183 were male and 173 female. 

 This gave a total of 362 male and 349 female weevils. The maxi- 

 mum flight by a fed male was 775 yards, by a fed female 350 

 yards, by an unfed male 225 yards, and by an unfed female 500 

 yards. The experiments also showed the average distance per 24 

 hours for a fed weevil as 63.3 yards, and for an unfed weevil, 66.6 

 yards. It was generally observed that the weevils flew with the 

 prevailing wind. 



Observations on the early spring movement of the weevil in Mis- 

 sissippi in 1910 showed the utility of the rotation of crops. During 



