14 
BULLETIN 911, U. S. DEPARTMENT OF AGRICULTURE. 
The data from Table XVII are summarized in Table XVIII. The 
average length of the prepupal period was 1.77 days, the maximum 
period 3 days, and the niinimum 1 day. where unsprayed foliage was 
supplied. Where the cocoons were formed on sprayed foliage the 
average prepupal period was 2.9 days, the maximum 5 days, and 
the minimum 1 day. The spray material apparently had a repellent 
action, for in another experiment where both sprayed and unsprayed 
foliage were equally accessible to larvae there were 226. or 63 per 
cent, of the total number of cocoons formed on unsprayed leaves and 
but 135. or 37 per cent, formed on sprayed leaves. Considerable 
mortality can be attributed to cocooning on sprayed leaves, since 
194 pupae were formed in 223 cocoons on unsprayed leaves, a mor- 
tality of 13 per cent as compared with the individuals that cocooned 
on sprayed leaves, where but 37 pupae were formed in 64 cocoons, 
showing a mortality of 42 per cent. 
TIME OF COCOONING OF FIRST-BROOD LARY.E. 
Table XIX. — Time of cocooning of 2,447 larost of the first ; tj i ' of the grape-berry moth, 
Sandusky, Ohio. 1917. 
Date of cocooning. 
Tidy 19. 
July 20. 
Julv 21 . 
July 22 . 
July 23 . 
T -.;:-24. 
Julv 25. 
Julv 26 . 
July 28. 
Julv 29. 
Julv SO. 
Julv 31 . 
Aug.l.. 
Aug. 2. . 
AMr.3.. 
Aug. 4. . 
Aug. 5. . 
A-;:. -?.. 
Aug.7.. 
AM-. S. . 
Aug. 9. . 
Auz. 10. 
A--. ::. 
Aug. 12. 
Aug. 13. 
Nnmbex 
of 
cocoons 
Ifean 
(lafly 
temper- 
ature. 
Date of cocoo nin g. 
: F. 
3 
71 
9 
7^ 
9 
76 
9 
76 
IS 
78 
10 
s-: 
31 
7S 
44 
BE 
55 
76 
' : 
72 
54 
Si 
12> 
87 
170 
88 
V-> 
88 
142 
7^ 
:■" 
71 
117 
58 
112 
H 
; : " 
7: 
15S 
76 
111 
i j 
y 
66 ! 
54 
6C 
Aug. 
Aue. 
Aug. 
Aug. 
Aug. 
Aug. 
Aug. 
Aug. 
Aug. 
Aug. 
Aug. 
Aug. 
Aug. 
Aug. 
Aug. 
Aug. 
Aug. 
Aus. 
r- 
Sept 
y 
Sept. 
Number 
of 
cocoons. 
Mean 
daily 
temper- 
ature. 
3 
6 
S 
Total 
°F. 
In Table XIX are given the complete records of cocooning for the 
first-brood larvae. Cocooning began on July 19 and continued until 
September S with a distinctly high period from July 30 until August S. 
The correlation with temperature is of interest, showing that as the 
mean temperature dropped below 70 c F. there was a drop in the rate 
of cocooning. 
