28 



The length of the pupal stage in large bolls has not been deter- 

 mined. It appears to be longer than in squares, but it certainly can 

 not occupy the same proportional part of the entire developmental 

 period that it does in squares. 



EFFECT OF BURYING SQUARES UPON PUPATION AND THE ESCAPE OF 



ADULTS. 



The experiments made upon this point were designed to ascertain 

 the value, if any, in the plowing under of squares as a means of 

 destroying the larva? and pupa? infesting them. But few experiments 

 seemed necessary to demonstrate the futility of this operation alone 

 as a means of controlling the weevil. 



Squares which were known to be infested with about half -grown 

 larva? were placed in glass jars and covered with several inches of 

 quite dry and fairly well pulverized earth. When examination was 

 made it was found that pupation had taken place normally while the 

 squares were buried under from 2 to 5 inc'hes of dirt. In no case 

 was pupation prevented, though a few weevils did not leave the 

 squares after having become adult. Altogether about 100 squares 

 were thus buried, and from them over 75 weevils emerged. 



In a portion of the preceding tests careful examination was made 

 to ascertain how far toward the surface the newly emerged weevils 

 had succeeded in getting before they perished. It should be noted 

 that these weevils had never fed, and they would have, therefore, less 

 strength and endurance than such fully hardened adults as might be 

 buried in the ordinary processes of field cultivation. Furthermore, 

 the soil used was of finer texture and more compactly settled than it 

 would be in the field. Twenty-seven weevils were found in this exam- 

 ination, their location varying from the bottom of the jar to their 

 having escaped through 4 inches of soil. A weighted average shows, 

 however, that each weevil had made its way upward through 2 inches 

 of dirt. We may infer, therefore, that had these squares been buried 

 under less than 2 inches of fairly well pulverized earth, as would be 

 the case from field cultivation, but a small percentage of them would 

 have failed to make their way out. As it was, fully three-fourths of 

 those leaving the squares made their way out through more than 2 

 inches of dirt. 



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 them- 

 selves, as shown by test experiment." Quite extensive experiments 

 are now being made at Victoria to test the ability of the fully fed 

 adult weevils to escape after being buried at various depths and in soil 

 containing various percentages of water. That the moisture content 

 exerts a great influence upon the texture of the soil is especially 

 noticeable in the black bottom lands of the Texas cotton belt. While 



