24 
BULLETIN 19, U. S. DEPARTMENT OF AGRICULTURE. 
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. 
Xo 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 hop per. 
Date of 
Num- 
Date of 
1 
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 
« 5 
Aug. 27 
3 
Aug. 5 
22 
Aug. 30 
5 
Aug. 7 
3 3 
Escaped. 
Killed. 
3 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 leaf hopper. 
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 
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. 
