SEASONAL IIISTOHV. 
37 
Table XIII. — Percentage of hibernating larvx of the grape root-worm as found in 
vineyards during the full of 1909 a' Xorth East, I'a. 
Curtis vineyard, in 
the valley. 
Algren vinevard, in 
the valley. 
Young vinevard, on 
the hill. 
Date of 
digging. 
Percent- 
age of 
larva? 
in cells. 
Date of 
digging. 
Percent- 
age of 
larvae 
in cells. 
Date of 
digging. 
Percent- 
age of 
larvae 
in cells. 
Oct. 5 
5 
Oct. 4 ... 
0 
Oct. 12... 
0 
Oct. 12. . . 
20 
Oct. 14... 
0 
Oct. 20. . . 
3 
Oct. 19... 
12 
Oct. 19. . . 
14 
Oct. 28... 
16 
Oct. 28... 
83 
Oct. 25. . . 
36 
Nov. 12.. 
33 
SPRING FEEDING OF THE LARVA . 
In the spring, with normally developed larvae, comparatively 
little feeding takes place. In the early part of May, 1909, the 
larva? in the rearing cages were still in their wintering cells, and 
the condition in the field in most places did not permit the larvae to 
become active previous to that time. Since occasional pupal cells 
were found on May 24 in the field (Table XIV) and continued to 
appear in rapidly increasing numbers, the time of spring feeding 
may, on an average, have lasted 20 to 25 days. 
Table XIV. — Appearance of larva- of the grape root-worm in cells previous to pupation 
at North East, Pa., 1909. 
Date of 
digging. 
Soil 
Total Number 
r-onflition number of larvae 
condition. oflarv . p _ in cells. 
Mav 19.. 
May 24.., 
Mav 25.. 
Mav 2& ! 
Mav 27.. 
May 29. . 
June 1 . . 
June 2. . 
June 3. . 
June 4. . 
Gravel. 
Sandv . 
do. 
Loam . . 
Gravel. 
Clav... 
Silt . . . . 
Clav. .. 
Cra vol. 
Silt. ... 
Gravel. 
230 . 
35 
140 
33 
32 
47 
79 
6 . 
63 
54 
Percent- 
age of 
larvae 
in cells. 
8.6 
2.S 
21.2 
6.2 
8.5 
29.1 
2.8 
39.0 
TIME AND MAKING OF THE PUPAL CELL. 
The pupal cells are found from 2 to 3 inches below the surface of 
the ground. Like the wintering cells, they are made by a peculiar 
rolling and twisting motion of the larva, whereby t ho cavity is 
enlarged, the earth becomes packed together, and the inside smoothly 
finished. The cell is quite spacious and would readily accommodate 
a larva twice the size of the ow ner. Usually 15 days are required to 
complete the pupal cell. As recorded in Table XVI, the average 
length of time spent by the larva* in the cell IS -1 days, which includes 
the post-larval stage described below. Should the cell be disturbed 
