THE GRAPE PHYLLOXERA IN CALIFORNIA. 89 
The experiments began June 27 and terminated September 7. Three 
hundred and ninety-seven migrants produced a total of 143 eggs 
from which no sexual forms developed. Thus the proportion of 
deposited eggs to migrants in 1913 was 1 to 3.2, while in 1914 it was 
1 to 2.75, and in 1911, 1 to 4.3. In 1914 four migrants each deposited 
four eggs, and three eggs were deposited in nine instances, but most 
of the eggs were laid singly. In no case could it be definitely said 
that eggs of more than one sex occurred in individual groups. About 
three times as many female eggs as male were deposited, and about 
one-fourth of the eggs were intermediate in size (probably males). 
The winged sexuparse died on the average two and one-half days 
after they were admitted to the cages, or about four days after they 
had transformed from the nymphal instar. 
In 1915 experiments were continued, migrants being secured from 
June 26 to October 27. Part of these were used in stencler and petri 
dishes, part in small circular rubber cells (■& inch high, 1J inches 
in diameter) mounted on microscope slides with cover glasses for 
lids, and a few on a living vine (Riparia). In the dishes small 
pieces -of vine, bark, or leaves were placed, leaves of the Champini 
being used mostly on account of the fact that the migrants prefer 
to deposit eggs on a tomentous leaf. The effect of variations in 
temperature and humidity was noted. 
A total of 1,961 migrants deposited in all 472 eggs, and 52 sexuals 
matured. Thus the proportion of eggs to migrants was approxi- 
mately 1 to 4.15. In the stender and petri dishes and on the living 
vine combined, 938 migrants deposited 167 eggs, a proportion of 5.6 
to 1, of which 16 sexuals matured. In the rubber cells mounted on 
microscope slides, 1,023 migrants deposited 305 eggs, a proportion 
of 3.3 to 1, and 36 sexed forms matured. The rubber cells therefore 
gave a greater proportion of eggs per migrant. Part of these cells 
were kept in a cellar and part inside a slide box in a room of the 
laboratory. The egg deposition was not appreciably different in 
these two situations, but the sexes under the almost constant tem- 
peratures of the cellar matured better than under the fluctuating 
temperatures of the room. Part of the dishes also were kept in the 
cellar and part exposed to light in the room. Those in the latter 
situation averaged more eggs per migrant, but the proportion of 
sexes which subsequently matured was similar to that of the migrants 
and dissimilar to that of the eg^s. 
It appeared at first that exposure to light induced the migrants to 
deposit a greater proportion of eggs and later appeared to have 
prevented a large proportion from maturing. Judging from the 
fact that the amount of light to which these eggs were subjected 
during their development was not greater than occurs under natural 
conditions, however, it would appear that this supposition is incor- 
