Puant Lick INJuRING FOLIAGE AND FRUIT OF THE APPLE 733 
The body is broadly pear-shaped, tending to globular in older speci- 
mens. The coloration varies greatly, not only in different individuals 
but also in the same individual during its life; in general the abdomen 
is yellowish green mingled with purplish brown, the sides being usually 
dark purplish brown; the head and the thorax are dark brown tending 
to purplish; around the cornicles and between them the color is often 
reddish; the legs are yellowish, with the femora, the distal ends of the 
tibiae, and the tarsi, fuscous to black. The entire body is covered with 
a fine white pulverulence. The head bears two short tubercles on the 
vertex. The eyes are black. The prothorax bears a pair of black dorsal 
tubercles as well as a lateral tubercle on each side. The remaining thoracic 
segment, and each of the first six abdominal segments, bear a pair of black 
lateral tubercles; the seventh and eighth abdominal segments, each have 
a transverse, dorsal, chitinous plate bearing two pointed tubercles, one on 
each side of the median line. The antennae are 6-jointed, fuscous at 
the base with the remainder black. The length and number of sensoria 
of the segments (fig. 112, c, page 685) are as follows: Segment III, 
0.32 mm., sensoria 0; Segment IV, 0.24 mm., sensoria 0; Segment V, 
0.22 mm., sensoria 1; Segment VI, 0.1 mm. + 0.22 mm., sensoria the 
usual group. 
The second generation 
In 1915 the first young were produced by the stem mothers on May 11 
and reached maturity on May 26. In general the second generation 
required from fourteen to twenty days to reach maturity and begin to 
produce young. 
One of the most characteristic features of this species is the congre- 
gation of the young about the mother. Each individual stem mother or 
group of mothers will have massed about it hundreds of young, so that the 
infested leaves may be so covered as to be actually more than one layer 
deep (Plate XIV). This gregarious habit soon causes the death of the in- 
fested leaves and the consequent migration of the aphids. However, when 
several stem mothers congregate on a single leaf, forced migration soon 
follows owing to the lack of available space. The young move actively 
and hurriedly, seemingly anxious to locate a suitable feeding ground. 
It is at this period that they are so frequently found congregated on the 
forming fruits or attacking the new and succulent unfolding foliage. 
