RECENT STUDIES OF THE MEXICAN COTTON BOLL WEEVIL. 31 



Table XX. — Number of generations of the boll weevil — minimum series on squares. 

 [First generation from last eggs of females that emerged from hibernation May 8 to 10.] 



Generation. 



Date. 



Period from 

 maturity 



to maturity 

 (about). 



Mean tem- 

 perature 

 for period. 



First generation: 



July 14-16. . . 



Days. 



°F. 





July 29-30. . . 

 Sept. 26-30.. 



81 



80.7 



Last generation: 







Oct. 13-15... 



78 



80.7 







HIBERNATION. 



The hibernation of variety thurberise in bolls of Thurberia is longer 

 than any other phase of this phenomenon for the species. The adults 

 mature in their cells before December, but remain therein until August 

 or later around Tucson, Ariz. When removed from the cells they 

 begin activity immediately. 



NATURAL CONTROL. 



Parasitism. — The parasitism of native weevil stages at Victoria 

 during the season was very slight. In spite of the large numbers of 

 infested squares and bolls collected in the field and held for the emer- 

 gence of weevils, not a single parasite was reared. Several hundred 

 infested squares and bolls were opened during the season and only 

 one parasite larva was found. 



Late in the season two lots of squares were sent to the writer from 

 Tallulah, La., by Mr. G. D. Smith. These were placed in cages for 

 the emergence of adults and five species of parasites emerged. These 

 were: Bracon mellitor Say; Catolaccus incertus Ashm.; Catolaccus 

 liunteri Cwfd.; Cerambycobius cyaniceps Ashm.; Eurytoma tyloder- 

 matis Ashm. Of these Bracon was much the more abundant. 



From the thurberise imported from Arizona only one parasite was 

 reared at Victoria. This was a specimen of Eurytoma sp. which had 

 parasitized a weevil larva. 



During September what threatened to be a serious outbreak of a 

 mite (probably Pediculoides sp.) appeared in the various breeding 

 series. This infestation spread rapidly over many of the shelves 

 where immature stages of weevils were being reared and soon killed 

 a considerable number of these. This infestation was evidently con- 

 trolled by the cool weather and no further trouble was experienced. 



Messrs. Schwarz and Barber found in Thurberia bolls two individ- 

 uals parasitized by Ichneumonoidea. 



Disease. — During the latter part of the season a curious epidemic 

 of deaths of newly emerged weevils occurred in one breeding series. 



