THE PEA APHIS WITH RELATION TO FORAGE CROPS. 



15 



specimens pale yellow-green at posterior end, becoming whitish, green 

 toward anterior end. Eyes maroon red. Antennas a little longer 

 than body; 6-segmented; segment I pale green; II pale green, with 

 a faint brownish tint; III, IV, and V pale, sometimes with a faint 

 brownish tint, and the tips dusky to blackish; base of VI pale brown- 

 ish to dusky, becoming blackish at the tip; filament of VI blackish. 

 Beak reaching to coxae of second pair of legs. Legs with femur pale 

 greenish yellow to greenish, the apex sometimes pale brownish, tibia 

 pale with a slight duskiness and the tip blackish, tarsus black. 

 Cornicles leaching just to or a little beyond tip of cauda. Cornicles 

 pale green to yellowish green at base, becoming pale dusky toward 

 apex, the extreme tip black. Cauda conoolorous with body. Cor- 

 nicles, cauda, and antennae usually semitransparent. 



Measurements from one specimen, immediately after placing in 

 balsam and before shrinkage occurs: Length of body, including 

 cauda, 1.70 mm, width, 0.64; length of cornicle, 0.40 mm. Measure- 

 ments of antennal segments: 



I. 



II. 



III. 



IV. 



V. 



VI base. 



VI 



filament. 



Mm. 

 0.12 

 .12 



Mm. 

 0.07 

 .07 



Mm. 

 0.278 

 .268 



Mm. 

 0.278 

 .295 



Mm. 

 0.370 

 .382 



Mm. 

 0.174 

 .157 



Mm. 

 0.73 

 .73 



Fourth instar, after third molt and between 127 and 128 hours old. — 

 (Described from two specimens, Aug. 19-24, 1912.) Body pale green, 

 sometimes with an indistinct yellowish area at the base of each cor- 

 niole, the head and thoracic segments sparsely covered with a whitish 

 pulverulence which gives them a paler green color. Eyes maroon red. 

 Antennae reaching beyond tip of cauda; segment I conoolorous with 

 head, II conoolorous with head or with a faint brownish tint; III, IV, 

 V, and base of VI pale brownish green, with the tips blackish; fila- 

 ment of VI blackish. Legs with femur pale green at base, becoming 

 faintly dusky toward apex, tibia pale brownish with tip blackish, 

 tarsus black. Cornicles reaching a little beyond tip of cauda, pale 

 green with the tip blackish. Cauda conoolorous with body. 



Measurements from one specimen, immediately after placing in 

 balsam and before shrinkage occurs: Length of body, 2 mm., length 

 including cauda, 2.25, width, 0.92; length of cornicles, 0.61 mm.; 

 length of cauda, 0.25 mm. Measurements of antennal segments: 



I. 



II. 



III. 



IV. 



V. 



VI base. 



VI 

 filament. 



Mm. 

 0.15 



.15 



Mm. 

 0.07 



.07 



Mm. 

 0.487 

 .504 



Mm. 



0.469 

 .452 



Mm. 

 0.504 

 .504 



Mm. 

 0.208 

 .208 



Mm. 

 0.887 

 .887 



