THE PEA APHIS WITH RELATION TO FORAGE CROPS. 21 
placed circular sensoria; IV bare; V with 14 to 18 circular ones, not 
including the usual distal sensorium, in a row on the distal two- 
thirds; base of VI with the usual ones. Beak reaching a])()ut to 
coxae of second pair of legs. Legs long and slender, th(^, femur 
blackish except- 
ing basal third, 
which is pale; 
tibia pale brown 
except tip, which 
is black, and the 
tarsus black. 
Cornicles as in 
winged male, 
pale at base, be- 
coming faintly 
dusky toward 
the tip; the apex 
black. Cauda 
pale green and 
agreeing with 
that of the 
winged male. 
Measurements 
(averages) from two specimens mounted in balsam, bodies shghtly 
shriveled: Length of body, 1.55 mm., to tip of cauda, 1.72, width, 
0.58; length of cornicles, 0.57 mm.; length of cauda, 0.26 mm. 
Measurements of antennal segments: 
Fig. 8. — Macrosiphum pisi: Wingless male, much enlarged; a, antenna of 
same, more enlarged. (Original.) 
T. 
IT. 
III. 
IV. 
V. 
VI l)ase. 
VT fila- 
ment. 
^fm. 
^fm. 
Mm. 
Mm. 
Mm. 
Mm. 
Mm. 
0. 156 
0.087 
0.817 
0.713 
0. 748 
0.2.52 
1.061 
.156 
.087 
.852 
.678 
.730 
.261 
1.009 
.156 
.087 
.817 
.651 
.748 
.269 
.991 
.156 
.087 
.817 
.661 
.739 
.243 
1.043 
Wingless oviparous female (fig. 9). — (Described from two speci- 
mens, December 12, 1912.) General color pale pea green or even 
yellowish green, the head paler and the abdomen posterior to the 
cornicles with a yellowish tint in some individuals. The eggs witliin 
the body often show through the dorsal abdominal wall. Eyes dark 
red. Antennje placed on prominent frontal tubercles; reaching to 
or a little beyond tip of body; very sparsely liairy; filament of s(^g- 
ment VI longest; sensoria usually as in the wingless viviparous 
femide, that is, only 1 or 2 sensoria at the base of segment III, but 
we have found exceptions where sc^gment III bore as many as 10 
sensoria in a row; segments I and II pale gvcvn or y<^Ilowis]i green, 
