66 HIBERNATION OF THE COTTON BOLL WEEVIL. 



ACTIVITY AS SHOWN BY DEVELOPMENT DURING NORMAL HIBERNATION 



PERIOD. 



Under the heading " Stages entering hibernation" the principal 

 data bearing upon developmental activity during the winter have 

 been given. (See pp. 13 and 14.) Additional data have also been 

 given in connection with "Shelter during hibernation. " (See Table 

 VII, p. 26; also Table IX, p. 28.) To these records for seasons pre- 

 ceding 1906-7 may be added the results of an experiment in collec- 

 tion of infested squares during this season. On November 23, 1906, 

 Mr. J. D. Mitchell collected 100 fallen squares which were supposed 

 to be infested. These were placed in the small cage under shelter 

 and out of the reach of sunshine. On February 10, 1907, he found 

 that 45 squares showed weevil emergence hulls, and the full number 

 of adults was found; however, all were dead at that time. An exam- 

 ination of the remainder of the squares revealed but one dead larva. 

 The others, apparently, had contained no weevil stages. Exception- 

 ally warm weather had prevailed during December and January, as 

 has been shown in figure 5. This had enabled the weevils to com- 

 plete their development and emerge, but all had starved to death in 

 the absence of any food supply. 



Some very interesting facts are also brought out by a closer study 

 of the records in connection with section 10 of each cage. As has 

 been shown, the experiment in these sections consisted of the collec- 

 tion of large numbers of unopened bolls probably infested. Several 

 of the bolls were buried under 2 inches of dirt and the remainder 

 were exposed upon the surface of the ground (PL X, fig. 1). Xo 

 partition was inserted to separate the weevils emerging from these 

 two lots of bolls, but in the case of section 10 at Dallas the first lot 

 of bolls was buried and a considerable period elapsed before the bal- 

 ance of the bolls, which were left upon the surface, was placed in 

 the cage. It was estimated that 3,000 bolls were buried at a uniform 

 depth of 2 inches under cover of heavy black soil. An examination 

 of 100 bolls showed 8 recently transformed but unemerged adults in 

 the bolls and 8 adults which had emerged were hibernating within 

 the protection afforded by the bolls. On this basis it appears that 

 about 480 weevils were buried in this lot of 3,000 bolls, half of them 

 being unemerged adults and half hibernating adults. No other mate- 

 rial was placed within this section, so that all weevils which were 

 subsequently found upon the screen must necessarily have found 

 their way through the 2 inches of soil under which the bolls were 

 buried. Counts made before the bolls to be placed on the surface 

 were put into the cage showed that 65 weevils at least had escaped 

 from the bolls to the screen forming the cage. This shows that fully 

 13.5 per cent of all the weevils buried, emerged and unemerged, had 



