THE GRAPE PHYLLOXERA IN CALIFORNIA. 45 
In 1913, between June 26 and November 14, a series of observations 
on fecundity under adverse food conditions was made. Among a 
large number of aphids, on two occasions only were as many as six 
eggs deposited in one day by a single individual. In the cellar, 431 
eggs were deposited in a total of 331 days (1.3 eggs per diem per 
aphid), and in an electric incubator, wherein a slightly higher 
temperature was maintained, 787 eggs were laid in a total of 463 days 
(1.7 eggs per diem per aphid). These averages were considerably 
less than corresponding ones found to result in the 1911 series, yet the 
insects raised in the incubator were subjected to higher temperatures 
than were those in 1911, raised in the cellar. 
Egg deposition on living vines. — During the years 1913, 1914, and 
1915, series of generations were raised on living vines in cages. These 
vines were all viniferse, and comprised the following varieties: 
Muscat, Zinfandel, Mission, Burger, Thompson's Seedless, and Gren- 
ache. The principal object in this work was to check up on the 
previous 2-year study of root cuttings under cellar conditions. The 
initial inoculations in 1913 were made with eggs laid by adults of the 
overwintered generation on Zinfandel vines in the vineyard, and thus 
no record of the egg production of the overwintered adults was 
secured in the cages. Of the first generation, records of 10 indi- 
viduals were taken, but a complete record of only one was made, and 
this adult, between June 25 and July 14 (20 days) , deposited 121 eggs, 
the largest number in a single day being 12. The 10 adults deposited 
482 eggs in 95 days, or an average of 3.1 eggs per diem per adult. 
Most of the individuals died early, and it is assumed that if they 
had been allowed to lay their full complement of eggs, the period 
of decline would have reduced this average. These adults were pro- 
duced, 7 on Burger roots and 3 on Mission roots. It appeared that 
those on the Mission were the more prolific. On both varieties 
some were situated on lesions they had caused to form. These aver- 
aged better in egg production than the others situated on the nor- 
mal root surface. Records for 14 adults of the second generation 
were taken. On a very healthy Mission root, living on lesions, 4 
adults averaged 4.5 eggs per adult per diem. On two less healthy 
Mission roots of the same cage vine, 6 averaged 2.4 eggs per adult 
per diem. On a very healthy Burger root 4 averaged 3.9. The 
longest egg-laying period for any adult of this generation was 26 
days and the maximum eggs per day 15. In all, 489 eggs were laid 
in 136 days, 3.6 eggs per adult per diem. 
The egg-laying period of this generation ran from July 8 to 
August 15, with an average temperature of 68° F. Four adults of 
the third generation deposited 284 eggs in 88 days, at an average 
of 3.2 eggs per diem per adult; the longest egg-laying period was 
28 days and the maximum number of eggs per diem was 8. These 
