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 about to 

 coxae of second pair of legs. Legs long and slender, the 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 slightly 

 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.) 



I. 



II. 



III. 



IV. 



V. 



VI base. 



VI fila- 

 ment. 



Mm. 



Mm. 



Mm. 



Mm. 



Mm. 



Mm. 



Mm. 



0.156 



0.087 



0.817 



0.713 



0.748 



0.252 



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 within 

 the body often show through the dorsal abdominal wall. Eyes dark 

 red. Antennae placed on prominent frontal tubercles; reaching to 

 or a little beyond tip of body; very sparsely hairy; filament of seg- 

 ment VI longest; sensoria usually as in the wingless viviparous 

 female, that is, only 1 or 2 sensoria at the base of segment III, but 

 we have found exceptions where segment III bore as many as 10 

 sensoria in a row; segments I and II pale green or yellowish green, 



