708 Rosert MATHESON 
of the wingless forms. The descendants of winged forms are indicated 
separately in the reproduction chart. 
On consulting the table it may be seen that the average productive 
period is nearly identical with that of the wingless forms of the second 
generation. The daily production of young is much higher, on the average, 
and the total production is almost equal to that of the stem mothers. 
The length of life, however, is considerably shorter, more nearly approach- 
ing that of the winged forms of the second generation. 
Description of stages 
Adult apterous female, third generation.— Length 1.7-2 mm.; width 
1 mm.; cornicles 0.4 mm. long. 
The general shape is pyriform. The color is light green to bright 
yellowish green; the head is yellowish, often shading to dusky yellow. 
The eyes are dark red, appearing almost black. The antennae are 
yellowish, with the distal half dusky. The distal ends of the femora, 
the tibiae, and the tarsi are black. The cornicles are cylindrical, black, 
gradually tapering, with a distinct flange at the distal end. The cauda 
and the genital plate are black. Lateral tubercles are present on the pro- 
thorax and on the abdominal segments. 
Adult winged female, third generation (Plate X XII):—The winged female 
of the third generation does not differ in any respect from that of the 
second generation and requires no separate description. 
The fourth generation 
At Ithaca the first individuals of the fourth generation reached maturity 
and began producing young on June 21. The production of young by 
this generation became more or less general about the last of June. The 
habits and activities of this and succeeding generations do not differ 
from those of the third generation and need not be discussed in any 
further detail. 
The reproductive capacity of the fourth generation presents some 
interesting features. The period of reproduction is longer than that of 
either the second or the third generation, and the daily number produced 
by each individual is considerably greater. The total average production 
is much higher than for any preceding generation. 
