34 THE GRAPE ROOT-WORM. 
Table IX. — Incubation period of eggs of the grape root-worm as observed in 1909 at 
North East, Pa. 
No. of 
° v^ r " 
tion 
Date. 
Days. 
No. of 
obser- 
tion 
Date. 
Days. 
Laid. 
Hatched. 
Laid. 
Hatched. 
1 
July 
15 
July 
29 
14 
49 
Aug. 
7 
Aug. 23 
16 
2 
...do. 
July 
30 
15 
50 
Aug. 
8 
Aug. 20 
12 
3 
July 
16 
...do. 
14 
51 
...do. 
Aug. 21 
13 
4 
July 
18 
July 
3i 
13 
52 
...do. 
Aug. 22 
14 
5 
...do. 
Aug. 
1 
14 
53 
...do. 
Aug. 23 
15 
6 
July 
i<j" 
...do. 
13 
54 
...do. 
Aug. 24 
16 
7 
July 
20 
...do. 
12 
55 
Aug. 
*9 
...do.... 
15 
8 
...do. 
Aug. 
"2 
13 
56 
...do. 
Aug. 25 
16 
9 
July 
21 
...do. 
12 
57 
Aug. 
16" 
...do.... 
15 
10 
...do. 
Aug. 
Z 
13 
58 
...do. 
Aug. 26 
16 
11 
July 
22 
Aug. 
2 
11 
59 
...do. 
Aug. 27 
17 
12 
...do. 
Aug. 
3 
12 
60 
Aug. 
U 
Aug. 26 
12 
13 
July 
23 
Aug. 
4 
12 
61 
...do. 
Aug. 27 
13 
14 
July 
25 
Aug. 
6 
12 
62 
...do. 
Aug. 28 
14 
15 
July 
26 
...do. 
11 
63 
...do. 
Aug. 29 
15 
16 
...do 
Aug. 
"i 
12 
64 
...do. 
Aug. 31 
17 
17 
July 
27' 
...do 
11 
65 
Aug. 
16 
...do.... 
15 
18 
July 
28 
Aug. 
"% 
11 
66 
...do 
Sept, 1 
16 
19 
July 
29 
...do 
10 
67 
Aug. 
'u 
...do.... 
15 
20 
...do 
Aug. 
"9" 
11 
68 
...do. 
Sept. 2 
16 
21 
...do 
Aug. 
10 
12 
69 
...do. 
Sept. 4 
18 
22 
July 
30" 
Aug. 
9 
10 
70 
...do. 
Sept. 5 
19 
23 
...do 
Aug. 
10 
11 
71 
Aug. 
is" 
Sept. 4 
17 
24 
...do 
Aug. 
11 
12 
72 
...do. 
Sept. 5 
18 
25 
...do 
Aug. 
12 
13 
73 
...do. 
Sept. 6 
19 
26 
July 
31 " 
Aug. 
11 
11 
74 
...do. 
Sept. 7 
20 
27 
...do 
Aug. 
12 
12 
75 
...do. 
Sept. 10 
23 
28 
Aug. 
T 
...do 
11 
76 
Aug. 
i9" 
Sept. 3 
25 
29 
...do 
Aug. 
13' 
12 
77 
...do. 
Sept. 4 
16 
30 
Aug. 
"2" 
...do 
11 
78 
...do. 
Sept. 6 
18 
31 
Aug. 
3 
...do 
10 
79 
...do. 
Sept. 7 
19 
32 
.. .do 
Aug. 
\X 
11 
80 
...do. 
Sept. 8 
20 
33 
.. .do 
Aug. 
15 
12 
81 
.. .do. 
Sept. 9 
21 
34 
...do 
Aug. 
16 
13 
82 
...do 
Sept. 10 
22 
35 
Aug. 
"4 
Aug. 
17 
13 
83 
...do 
Sept. 11 
23 
36 
Aug. 
5 
Aug. 
16 
11 
84 
...do. 
Sept. 12 
24 
37 
. . .do 
Aug. 
17 
12 
85 
Aug. 
26' 
Sept. 6 
17 
38 
...do 
Aug. 
18 
13 
86 
.. .do. 
Sept. 7 
18 
39 
...do 
Aug. 
19 
14 
87 
...do. 
Sept. 8 
19 
40 
Aug. 
Aug. 
18 
12 
88 
...do. 
Sept. 9 
20 
41 
...do 
Aug. 
19 
13 
89 
Aug. 
26" 
Sept. 18 
23 
42 
...do 
Aug. 
20 
14 
90 
...do. 
Sept. 19 
24 
43 
...do 
Aug. 
21 
15 
91 
Sept. 
3" 
Sterile. 
44 
Aug. 
Aug. 
18 
11 
92 
Sept, 
10 
Sterile. 
45 
.. .do 
Aug. 
19 
12 
93 
Sept. 
12 
Sterile. 
46 
...do 
Aug. 
20 
13 
94 
Sept, 
13 
Sterile. 
47 
...do. 
Aug. 
21 
14 
95 
Sept. 
14 
Storile. 
48 
...do 
Aug. 
22 
15 
96 
Sept. 
20 
Sterile. 
Table X. — Summary of Table IX; time of incubation of grape root-worm eggs for 1909. 
Incubation. 
Average. 
Maximum. 
Minimum. 
Days. 
Days. 
Days. 
For the entire egg period 
14. 67 
24 
10 
For the maximum egg period, July 22-Aug. 8, inclusive 
12.3 
16 
10 
Eggs laid at approximately the same date by the same female 
varied in the time of hatching to the extent of several days. The 
embryological development becomes particularly prolonged later in 
the season with the advent of colder weather. All the eggs laid dur- 
ing the month of September failed to hatch. 
The rate of hatching of eggs in the field has been recorded in 
Table XI. 
