155 



escaped, from an average depth of soil of 1 inch. Taking* all stages 

 of the weevil together, 35.2 per cent died without escaping from the 

 soil. 



The conditions prev^ailing in these tests were much more severe than 

 the J could be made in the field, since cultivation can be practiced only 

 after the soil has become comparatively dry. Under field conditions 

 burjdng of squares and adults would be deepest when the soil is quite 

 dry and well pulverized. These conditions have been found quite 

 favorable to the escape of the adults. Observations made in the field 

 have shown that under the most favorable conditions by the ordinary 

 methods of cultivation weevils and squares upon the surface of the 

 ground will be buried hardly deeper than 1 inch. 



In 1896 Mr. C. L. Marlatt noted that "the weevils can escape from 

 loose soil when buried to a depth of 3 inches, but when artificially 

 embedded 8 inches in moist soil they are unable to extricate themselves, 

 as shown by test experiment." 



BURYING WEEVILS IN AUTUMN. 



Among 100 weevils buried on or after November 23, 1903, under 

 from 2 to 6 inches of soil containing from 9 to 19 per cent of water, 

 only six weevils succeeded in reaching the surface. Four of those 

 escaping, and one which was still buried in the earth, were found to be 

 alive when examination was made on March 16, 1901. All the remain- 

 ing weevils appeared to have died where they were buried. Those 

 escaping had made their way out through 2 inches of soil containing 

 about 9 per cent of water. The greatly increased effectiveness of 

 burying under fall conditions is apparent from these results. 



CONCLUSION. 



The suggestion has frequently been made that the plowing under of 

 squares and weevils during the ordinary work of cultivation of the 

 crop will effect their destruction. This has been shown to have but a 

 limited effect in that direction. This is not at all the fundamental idea 

 in the recommendation which is made b}^ the Bureau of Entomology 

 for thorough cultivation of the crop. The present indication is that 

 the beneficial effect of thorough cultivation lies in the direct influence 

 which that practice exerts upon the steady and rapid growth of the 

 cotton by favoring the production of squares, the formation of bolls, 

 and the early maturity of the crop, rather than by the destruction of 

 the weevils by bur3nng them while in the squares or after they have 

 become adult. It is fairly open to question whether the burying of 

 squares early in the season is not of sufficient advantage to the weevils 

 in the squares at that period to offset any mortality which might be 

 produced b}^ the practice. 



