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BULLETIN 19, U. S. DEPARTMENT OF AGEICULTUEE. 



the ground so that the dead adults falling from the' foliage of the 

 vine might be more easily seen. An examination for dead adults 

 was made every few days by looking for them upon the black cloth. 

 No dead adults were observed to July 12. On July 12 the adults 

 were transferred to a new cage to avoid confusing them with newly 

 transforming adults. During this operation 18 adults either escaped 

 or were killed. In this new cage 82 adults were placed. Dead adults 

 were found in the cage on the dates shown in Table VIII. 



Table VIII. — Longevity of overwintering adults of the grape leaf hopper . 



Date of 



Num- 



Date of 



Num- 



examina- 



ber 



examina- 



ber 



tion. 



dead. 



tion. 



dead. 



1912. 





1912. 





July 17 



1 



Aug. 12 



3 



July 28 



3 



Aug. 17 



2 



Aug. 2 



2 



Aug. 23 



4 



Aug. 3 



i 5 



Aug. 27 



3 



Aug. 5 



22 



Aug. 30 



5 



Aug. 7 



3 3 







Escaped. 



2 Killed. 



1 Killed by spider. 



On August 30 these adults were again transferred to a new cage to 

 avoid their being confused with newly transforming adults. During 

 this transfer 10 adults were either killed or escaped. In the new 

 cage there were 39 adults. The number of dead adults found in this 

 cage is given in Table IX. 



Table IX. — Longevity of overwintering adults of the grape leafhopper. 



Date of 

 examina- 

 tion. 



Num- 

 ber 

 dead. 



Date of 

 examina- 

 tion. 



Num- 

 ber 

 dead. 



1912. 

 Sept. 4 

 Sept. 7 

 Sept. 12 

 Sept. 14 



4 

 3 

 1 

 6 



1912. 

 Sept. 20 

 Sept. 26 

 Oct. 2 



3 



7 

 6 



The last examination was made on October 2, when there were 

 four adults still living. Hence it is evident that some of the over- 

 wintering adults may remain on the vines during the entire growing 

 season. Yet in vineyards that were the object of frequent visits 

 during the seasons of 1911 and 1912 it was observed that there was 

 a period, about the middle of the summer each season, when a de- 

 crease in the number of hibernating adults was quite noticeable. 

 During the season of 1911 this period of apparent decrease of over- 

 wintering adults was about June 25. In 1912 it was about July 15. 

 In both instances this decrease in number of adults occurred about 

 two weeks before the transformation of the new brood in large 

 numbers to adults. 





