44 
these pots was about the same as that occurring 2 feet below the soil 
surface. In the spring of 1915. on the Champion. Lenoir. Catawba, 
and Isabella, the phylloxeras began to grow about March 1. On the 
first three the bulk of the hibernants were mature April 6. but on 
the Isabella, which was moribund, more than half were unmolted. 
This vine was not retained further, but, considering the condition 
of its roots, it is not probable that any of the phylloxera would 
have matured. The vine was too weak to send out new rootlets, and 
the roots showed much decay. The abundance of phylloxeras the 
summer previous had doubtless caused this weakness. 
THE RADICICOLE. 
EGG DEPOSITION. 
The adult radicicole commences to deposit eggs within 48 hours 
after the final molt. Occasionally there occur abnormal individuals 
which delay deposition of eggs as much as two weeks, and again 
there are others which fail to deposit eggs but continue alive for 
some weeks. 
Egg deposition on severed roots. — Table III gives the summarized 
record of the egg deposition of radicicoles under cellar conditions 
during the years 1911-12. 
Table III. — Summarized record of egg deposition of radicicoles of the grape 
phylloxera under cellar conditions during 1911-12, Walnut Creek, Calif. 
Num- 
ber of 
adults. 
Egg-laying period for gener- 
ation. 
Number of eggs per Days in period of 
adult. deposition. 
Aver- 
age 
num- 
ber of 
eggs 
per 
adult 
per 
day. 
Gener- 
ation. 
Maxi- 
mum. 
Mini- 
mum. 
Aver- Maxi- 
age. mum. 
Mini- 
mum. 
Aver- 
age. 
1 
52 
45 
57 
17 
2 11 
27 
Apr. 21 to Oct. 1 
347 
486 
287 
266 
119 
137 
4 
10 
2 
3 
31 
4 
84. 6 110 
192. 96 
102. 106 
141. 8 96 
67. 2 ■ 83 
2 
5 
1 
2 
23 
3 
55.3 
46.3 
48.5 
44 
41.7 
21.5 
1.53 
1 
2 
3 
May 27 to Sept. 23 
June 29 to Nov. 6 
Aug. 4 to Dec. 7 
4.1 
2.1 
3.2 
4 
Sept. 5 to May 15, 1912. . . 
1.6 
3 5-10 
Apr. 26 to Oct. 6 
1.7 
1 Overwintered generation. - Including 3 individuals which matured in 1912. 3 Throughout 1912. 
Xeglecting the series of generations 5 to 10. the individuals of which 
suffered through abnormal food and other conditions, it is shown in 
Table III that the aphids of the second generation were the most 
prolific. One aphid deposited -186 eggs in 79 days, an average of 6.3 
per diem. The greatest number of eggs laid within 24 hours by a 
single adult was 23 and the longest laying period covered 110 days. A 
true seasonal average of the number of eggs deposited by each aphid 
was 117 for 1911 and a similar average of the number of eggs per 
diem per aphid about 2J. 
