GRAPE-BERHY MOTH IN NORTHERN OHIO. 
17 
of the first-brood moths began before the spring brood emergence 
ended. This means that moths were emerging practically from 
grape bloom until grape harvest; the majority of all emergence, 
however, occurred in two well-defined periods, as shown graphically 
in figure 2. 
PROPORTION OP SEXES OF FIRST-BROOD MOTHS. 
Table XXIII. — Proportion of sexes of first-brood moths of the grape-berry moth, 
Sandusky, Ohio, 1917. 
Sex of moths. 
Number 
ofmoths. 
Percent- 
age of 
sexes. 
Male 
316 
1,412 
41 
18.28 
Female 
81.72 
Undetermined 
Total 
1,769 
100.00 
The high percentage of female moths helps further to explain the 
occurrence of a large second brood of larva?. 
LIFE CYCLE OF THE FIRST GENERATION. 
Table XXIV.— Life cycle of the first generation of the grape-berry moth as determined 
from observations on the separate stages; summaries from the previous tables, Sandusky, 
Ohio, 1917. 
Summary 
Stage. 
Number 
of indi- 
viduals. 
Days of duration of stage. 
from Table 
No.— 
Average. 
Maxi- 
mum. 
Mini- 
mum. 
XV 
Egg stage 
165 
70 
4.39 
20.62 
14.78 
8 
37 
32 
3 
14 
XVI 
Length of feeding period of larvae 
XXI 
XXI 
[Making of cocoon and pupal stage 
1,254 
Q 
Total life cycle 
39.79 
77 
23 
The life cycle as here presented is seen to average 39.79 days with 
77 days as the total of the maximums and 23 days as the total of the 
minimums. To the average of 39.79 should be added the period 
between moth emergence and oviposition, which is usually 3 days, 
thus making the total life cycle 42.79 days. 
SECOND GENERATION. 
INCUBATION PERIOD OF SECOND-BROOD EGGS. 
One record only was secured concerning the incubation period of 
second-brood eggs, and that late in the season when the temperature 
was comparatively low. Twenty- two eggs were deposited on Sep- 
tember 1, the black spot was evident on September 9, and the eggs 
hatched September 11, 10 days after oviposition. 
7678°— 20 3 
