752 RoBert MATHESON 
Second instar.— The color of the second instar is yellowish green, with 
the characteristic bright green diamond-shaped areas beginning to show 
on the dorsal surface of the abdomen; these, however, do not yet form 
a marked continuous line as appears in the later instars; the head is’ 
dark green; the legs and the cornicles are brown to almost black. The 
cornicles are still very short. 
Third instar.— The third instar differs little from the second in color | 
markings. The bright green diamond-shaped areas on the dorsum of 
the abdomen now form a continuous line, distinctly differentiating this | 
species from the other two. | 
Fourth instar.— This instar is practically identical with the mature 
stem mother and does not require a separate description. 
Mature stem mother (Plate XXI).— Length 2-2.15 mm.; width 1.2- 
1.3 mm. 
The general color is yellowish green, the sides darker green; there is 
a broad median dorsal green stripe; at each segmental suture this stripe 
broadens out laterally, giving a somewhat diamond-shaped appearance 
to the green area of each segment; the distal ends of the antennae and) 
the tibiae, the tips of the cornicles, and the tarsi, are dusky to black;| 
around the base of the cornicles and between them there is frequently 
a reddish yellow area; the head is concolorous with the body; the eyes| 
are black. The cornicles are cylindrical, slightly constricted at base and 
apex, with flaring tips (fig. 113, c, page 702). The antennae (fig. 112, B 
page 685) are 5-jointed. The length of the antennal segments is as follows: 
Segment IIT, 0.32 mm.; Segment IV, 0.09 mm.; Segment V, 0.24 mm. 
| 
The second generation 
The young nymphs of the second generation feed almost exclusively 
on the foliage; rarely have they. been found on the developing fruit. 
At Ithaca the majority of this generation acquire wings and migrate to 
the summer host plants. A small proportion are wingless viviparous 
females and continue to produce young on the apple. : 
Description of stages 
First instar.— The young nymph is yellowish green in color, with the? 
mid-dorsal green stripe plainly visible; the tips of the antennae, the? 
