716 Rospert MATHESON 
The oviparous female is particularly distinguished from the females of the 
other generations by the position of the sensoria on the antennae and their 
presence on the hind tibiae. These are shown in figures 118, a, and 119, a. 
Fig. 119. HIND TIBIAE OF OVIPAROUS FEMALES 
A, Aphis pomi; B, A. avena:; C, A. sorbi. All drawn to same scale 
The male (Plate X XIII) 
Length 0.96-1.2 mm.; width 0.48-0.56 mm.; cornicles 0.16 mm. long. 
The males are wingless. The general color is brownish yellow; the 
head and the antennae are dusky to black; the cornicles, the cauda, and 
the genitalia are black; the distal ends of the femora, the tibiae, and the 
tarsi are dusky to black. The cornicles are cylindrical, slightly tapering 
toward their distal ends, with a slight flange-like expansion at their tips. 
The antennae are 6-jointed, nearly equaling the length of the body. The 
sensoria are as shown in figure 118 p. The length of the antennal seg- 
ments and the number of sensoria of each are as follows: Segment ITI, 
0.23 mm., sensoria 8-12; Segment IV, 0.22 mm., sensoria 8-11; Segment V, 
0.2 mm., sensoria3; Segment VI, 0.09-+0.24 mm., sensoria the usual group. 
The egg 
The egg is oval in form, slightly flattened on the side next the bark. 
The length is from 0.48 to 0.56 mm. When first laid it is bright yellow 
