102 THE MEXICAN COTTON-BOLL WEEVIL. 



This is a task quite comparable with that of seeking for the pro- 

 verbial needle, and it is not surprising that the results have been 

 very meager. The fact, however, that traces of weevils have been 

 found in these examinations indicates that weevils may find shelter 

 under such conditions. 



Farmyards, seed houses, barns, ginneries, and oil mills also afford 

 favorable shelter for weevils. Especially in ginneries and seed 

 houses the weevils become concentrated with the cotton or seed and 

 frequently may be found in large numbers within or around these 

 buildings. In connection with this subject the reader is referred to 

 a fuller discussion of the significance of ginneries and oil mills in the 

 distribution of weevils and of the methods recommended for con- 

 trolling them. 1 



In order to have a basis of comparison of the various kinds of 

 shelter, many cage experiments have been conducted. In Table 

 XXXVII will be found a comparison of the survival in the cages at 

 Keatchie, La., for weevils installed November 23 and 29. 



Table XXXVII. — Favorable conditions for hibernation determined by rank in per- 

 centage of weevils surviving at Keatchie, La., in 1905-6. l 



Nature of shelter. 



Weevils 

 put in. 



Weevils survived. 



Number. Percent 



Ordinary field stalks, grass, etc 



Brush, leaves, stumps, logs; stalks standing 



Same as above, but stalks removed 



Cotton seed, piled but uncovered; stalks standing. 



Absolutely bare ground 



Cotton seed piled and covered; stalks left standing 



2,000 

 2,500 

 3,300 

 2,000 

 2,000 

 2,000 



4.65 

 3.56 

 2.12 

 1.50 

 1.50 

 1.15 



1 From Bull. 77, Bureau of Entomology, p. 42. 



It is evident from these observations that ordinary field conditions 

 where stalks are allowed to stand together with the grass and leaves 

 littered over the ground are as favorable as any other for successful 

 hibernation. One fact should be emphasized in regard to classes of 

 shelter which have been mentioned as occurring within cotton fields, 

 i. e., that it is possible, as a rule, to destroy or remove practically all 

 of them. Undoubtedly the burning of cotton stalks, weeds, grass, 

 and other rubbish is the easiest and most effective method of destruc- 

 tion where it can be practiced. Next to this in importance would 

 be the destruction of the stalks by a stalk chopper and plowing under 

 all the rubbish. In the latter case it must be stated that many weevils 

 which, under dry conditions, are buried not more than 2 inches will be 

 able to escape through the soil and may then find shelter near, if not 

 within, the field. 



i Farmers' Bull. 209, U. S. Dept. of Agriculture, "Controlling the Cotton Boll Weevil in Cotton Seed and 

 at Ginneries." 



