THE GRAPE PHYLLOXERA IN CALIFORNIA. 
85 
Fig. 8. 
Phylloxera vitifoliae: Types of antennae of 
intermediates. Greatly enlarged. 
eyes were absent, and in no case were ocelli discernible. In most in- 
dividuals there were two sensoria on the last antennal joint, and in 
one antenna there were two small basal sensoria and the usual 
apical sensorium, making 
three in all. The basal sen- 
soria were not in any case 
as large as those of the 
winged migrant. The an- 
tennae and legs were about 
as long as those of the 
nymph, noticeably longer 
on the average than those of 
the individuals of group 2, 
which in turn were longer 
than those of the two indi- 
viduals of group l. 10 It would appear, therefore, that greater devel- 
opment of wing pads and compound eyes is complemented with a 
lengthening of legs and antennae and a tendency to bear the extra 
sensorium of the winged forms. The femora exceed the tibiae in 
length. 
There is among the intermediates a tendency toward asymmetry. 
This was remarked in Italy and has also appeared in California. 
One eye may have more facets than the 
other ; the lengths of antennae and legs 
may differ in individuals, those of one 
side being longer than their counter- 
parts, and one antenna may possess 
more sensoria than the other. 
In two instances the fourth stage of 
intermediates was observed in Califor- 
nia. In one case an individual of group 
3 molted from what appeared, under 
the lenses of the binocular microscope, 
to be a true nymph. In the other case 
an example of the same group molted 
from an insect which itself resem- 
bled a nymphical; in fact, after the 
molt the individual did not appear 
to have changed its structure at all. 
In both fourth and fifth instars the 
wing pads were large and "fleshy." 
From three individuals, all of group 3, eggs were obtained. These 
eggs could not be differentiated from eggs laid by wingless raclici- 
coles. One nymphical deposited two eggs, which were lost. An- 
Fig. 9. — Phylloxera vitifoliae: Nymph 
and antenna of newly molted in- 
sect, for comparison with interme- 
diates. 
10 The insect depicted 
figure 6. 
in figure 7 is considerably less enlarged than that represented in 
