HIBERNATION AND DEVELOPMENT OF BOLL WEEVIL. 9 



30 live and 40 dead adults, and 5 dead larvae. Many of these weevils 

 had just transformed from pupae and were still soft and light brown. 

 Some transformed after being received. But one live larva was found 

 in all the material examined. Mr. Allgood wrote the writer that these 

 bolls had been collected from stalks in a neighbor's field in which there 

 were 7,000 plants to the acre, that each plant held from 12 to 15 bolls, 

 and that the bolls sent in were picked at random from the field. Upon 

 this basis, disregarding the live pupae but counting the 30 weevils 

 which were found alive as having survived the winter, there would 

 have been 10,500 weevils per acre in the spring. If but one- third of 

 these survived there would have been 3,500 per acre, or more than 

 have ever been recorded in any field observations. If, as seems quite 

 possible, but one-fifth survived, there would have been 2,100 per acre, 

 which is approximately the number which survived in Lavaca County 

 under the favorable weather conditions of the winter of 1903-4. Mr. 

 Allgood wrote that cattle were then grazing in these fields, but it 

 is doubtful if the cattle would have eaten many of the dry hardened 

 bolls. In another lot of 48 bolls and forms sent b}^ Mr. Allgood at 

 the same time, we found 18 uninhabited large bolls, 15 forms, and 15 

 small bolls. These contained 17 live weevils, 4 live pupae, 4 dead 

 pupae, and 2 dead larvae, or one live weevil to every 3 bolls or forms. 

 These weevils were confined in a wooden box in the laboratory and 

 were still alive April 10, but later died, as no food could be supplied 

 them at that time under temperature conditions such that they would 

 normally have emerged. Doubtless they would all have emerged 

 early in April at Devine. The temperature at Pearsall, the nearest 

 weather station to Devine, during the winter was as follows: Decem- 

 ber, 1902, mean 54°, lowest 30°; January, 1903, mean 51.8°, highest 

 80°, lowest 29°; February, 1903, mean 52.8°, highest 77°, lowest 23°; 

 March, 1903, mean 60.6% highest 82°, lowest 38°. 



It will be seen that there were but few days during the winter in 

 which the temperature was below freezing. The total mean tempera- 

 ture for these four months at Pearsall was but 63° less than the total 

 normal mean for southwestern Texas during this time, and the rain- 

 fall at Pearsall was but 6.34 inches greater than the normal for south- 

 western Texas, no normal records for Pearsall being given. The 

 total rainfall of these months is normally but 7.51 inches for southern 

 Texas, so that the rainfall was nearly double the normal and the 

 winter would appear to have been exceedingly unfavorable for the 

 hibernation of weevils in their usual places of shelter. However, 

 weevils which developed in the unopened bolls were almost entirely 

 protected from the excessive rainfall, and the temperature being nor- 

 mal the} 7 would probably survive, while those weevils which went into 

 hibernation in all usual places in the fall would doubtless have suffered 

 an excessive mortality due to the unusual rainfall. 

 7036— Bull. 63—09 2 



