32 



INSECT ENEMIES OF THE BOLL WEEVIL. 



A series of examinations was made in the vicinity of Victoria, 

 Tex., in 1907 and 1908. On October 9, 1907, Mr. Cusliman noted 

 that fall destruction of the cotton was being carried on quite exten- 

 sively, but in different manners. On the east side of the river, south 

 and east of town, was an area in which practically all of the cotton 

 had been defoliated by the cotton leaf-worm. This area was sepa- 

 rated by the river and by a ^vide strip of huisache timber from 

 other cotton areas. In other directions were located fields stripped 

 by grazing, some that were plowed under, and one field only was 

 found which had received no treatment. 



On June 17, 18, and 19, 1908, fallen squares from several of these 

 fields were examined, with the following results: 



Table XVII. — Boll-weevil mortality in various cotton fields, Victoria, Tex., 1908. 



Treatment, 1907. 



Total 

 stages. 



Total. 



Percentage of mortality, 1908. 



Climate. 



Preda- 

 tors. 



Parasites. 



Destroyed stalks, September, 



Plowed, October 



Plowed, December 



Grazed, October 



Do 



Defoliated 



Do 



Do 



314 

 296 

 354 

 144 

 290 

 480 

 513 

 375 



18.18 

 13.80 

 60.70 

 44.40 

 37.50 

 29.30 

 52.80 

 23.70 



5.43 



7.70 

 14.40 

 24.30 

 25.50 

 20.60 

 27.00 

 16.50 



4.14 

 3.00 

 41.20 

 15.97 

 7.20 

 2.50 

 11.10 

 3.10 



9.23 

 3.00 

 5.08 

 4.16 

 4.80 

 6.20 

 14.40 

 4.50 



These striking differences in the percentage of control can not be 

 attributed to the differences of treatment in 1907, although that 

 may have had a bearing. The different fields had different weeds 

 and plants surrounding them, they received different treatment in 

 the spring of 1908, and there are many other reasons why no one 

 basis of comparison can be chosen. The table is offered to illustrate 

 how wide a difference in natural control can be found in fields only a 

 few nliles apart and proves conclusively the value of individual effort 

 in the fight against the weevil. 



Numerous other instances are contained in the notes that are quite 

 as striking as the one to which reference has been made. There is 

 every reason why each planter should follow out as complete a pro- 

 gram against the weevil as he can, because each effort reduces the 

 total infestation of his neighborhood. 



7. CLIMATIC CONSIDERATIONS. 



The chmate of the hibernating season of 1906-7 was very unusual, 

 so much so that the boll weevil hardly became quiescent, and the 

 emergence was largely during March, whereas normally it is in 

 April. The boll-weevil parasites mature simultaneously with the 



