THE GEAPE LEAFHOPPER IN THE LAKE EEIE VALLEY. 
23 
TERMINATION OF OVIPOSITION OF ADULTS OF THE FIRST BROOD. 
First-brood adults placed in cages with grapevines after August 10 
gave no evidence of further reproduction, for nymphs failed to appear 
on the foliage. About 50 adults were placed in each of five separate 
cages on August 12, 15, 20, and 27, and September 9. No nymphs 
appeared in any of these cages, indicating that the season of egg 
deposition for them, at least, had closed. 
Since there is a long period over which the nymphs of this first 
brood transform to adults, an endeavor was made to determine the 
date at which these later transforming adults would fail to reproduce 
during the same season. With this end in view, on July 24, 1912, 
100 nymphs of each of the five nymphal stages were placed in five 
separate cages on the foliage of a small Concord grapevine in order 
to ascertain if the adults transforming from any or from all of the 
nymphs in these five cages would copulate and produce another 
brood of nymphs. Frequent examinations were made of all of these 
cages during the remainder of the season. All of the nymphs in the 
five cages transformed to adults, but no mating of the adults was 
observed nor did any nymphs of a new brood appear upon the foliage 
of the vines in the cages. 
On the other hand, in another cage in which 50 adults were placed 
on July 22, to determine to what extent and how late in the season 
they continued to reproduce, nymphs continued to hatch as late as 
September 15. Below is given the daily hatching record of nymphs 
from these 50 adults: 
Table VII. — Hatching record of nymphs from 50 adult grape leaf hoppers placed in 
confinement July 22, 1912. 
Number 
Number 
Number 
Number 
Date. 
of 
nymphs 
Date. 
of 
nymphs 
Date. 
of 
nymphs 
Date. 
of 
nymphs 
removed. 
removed. 
removed. 
removed. 
1912. 
1912. 
1912. 
1912. 
Aug. 12 
38 
Aug. 22 
143 
Aug. 31 
52 
Sept. 9 
25 
Aug. 13 
132 
Aug. 23 
76 
Sept. 1 
96 
Sept. 10 
13 
Aug. 14 
172 
Aug. 24 
83 
Sept. 2 
108 
Sept. 11 
8 
Aug. 15 
245 
Aug. 25 
50 
Sept. 3 
115 
Sept. 12 
6 
Aug. 16 
173 
Aug. 26 
137 
Sept. 4 
95 
Sept. 13 
4 
Aug. 17 
139 
Aug. 27 
108 
Sept. 5 
89 
Sept. 14 
2 
Aug. 19 
272 
Aug. 28 
5 
Sept. 6 
48 
Sept. 15 
6 
Aug. 20 
250 
Aug. 29 
73 
Sept. 7 
49 
Aug. 21 
131 
Aug. 30 
47 
Sept. 8 
24 
LONGEVITY OF OVERWINTERING ADULTS. 
An effort was made to determine the length of life of overwintering 
adults. Owing to the great activity of the adult leaf hoppers it was 
found to be exceedingly difficult to keep a record of each individual- 
In order to secure some data on this point 100 overwintering adults 
were placed on a small Concord vine inclosed in an arc-light globe 
cage on May 31. A black cloth was stretched over the surface of 
