THE CONCHUELA. 63 



taUa 14 by tabla 15 (which was planted in corn), showed on July 29 

 an average of between 2 and 3 adult conchuelas for each 100 plants. 

 No actual estimates of the numbers of the insects present had been 

 previously made, but from casual observation it is practically certain 

 that the general decrease in numbers had occurred on this tabla as 

 well as on the others examined. Other observations in various places 

 confirm the belief that the diminution in the numbers of the insects 

 occurred generally throughout the plantation. Messrs. J. P. Conduit 

 and J. A. Vaughan informed the writer that after August 1 the bugs 

 never appeared anywhere on the plantation in what seemed de- 

 structive abundance, although a few were constantly present in va- 

 rious sections. During the first week in December, no frost having 

 occurred, the author could find no specimens of the conchuelas in the 

 cotton fields, although within two weeks a live specimen had been 

 seen at the gin, having been accidentally brought in with seed 

 cotton. 



The seasonal history at Barstow, Tex., in 1905, showed a similar 

 record to that at Tlahualilo. The conchuela there was very abundant 

 about the middle of July, and, while by no means uncommon on 

 August 11 and 12, it was evident that a considerable reduction in 

 numbers had taken place during the previous 2 or 3 weeks. On 

 September 12 it was found that only a slight further reduction in 

 the number of adults had taken place, but nymphs were compara- 

 tively scarcer. A month later Mr. J. C. Crawford, of the Bureau 

 of Entomology, found that nymphs in the fourth and fifth instars 

 were much more abundant than they had been on the dates of the 

 two preceding examinations ; the adults were slightly more abundant 

 than on September 12, and mostly soft, indicating that they had 

 recently matured. On November 14 Mr. Crawford, in a few hours' 

 search where the bugs had previously been abundant, could find no 

 nymphs and only a half dozen adults, all of which had attained the 

 ordinary degree of firmness and were therefore not recently matured 

 as were those collected on the preceding visit. 



HIBERNATION. 



The conchuela appears to hibernate exclusively in the adult stage. 

 Observations have been recorded under the subject of duration 

 of the nymphal stages w^hich indicate that it is highly improbable 

 that immature forms ever survive even one-half of the winter season. 

 No field observations have been made upon the hibernatk)n of this 

 species owing to the fact that as cold weather approached the sur- 

 viving adults were so scarce, even where they had been previously 

 most abundant, that to obtain positive results more attention than 

 it has been practicable to give would have been required. Nineteen 



