The pea aphid is about 3/16 inch long and 1/16 inch wide at maturity. It ranges from light to dark green in color. A small percentage of pea aphids may be pink or pinkish tinged. Cornicles are long and blackish towards the tip. The pea aphid can be distinguished from the blue alfalfa aphid by the narrow dark band at the tip of the third antennal segment, whereas the blue alfalfa aphid's third antennal segment is uniformly brown. Winged pea aphids have a light brown thoracic area, while this region on the blue alfalfa aphid is dark brown. In general the pea aphid is larger than the blue alfalfa aphid and lacks its dark blue-green color.