Wingless potato aphid adults are 1.7 to 3.6 mm in length, which makes them the largest of the potato-colonizing aphids in Atlantic Canada. The body is elongate, wedge-shaped, yellowish-green to pink and darker along the middle of the back. The head has prominent antennal tubercles which are directed outwardly. Winged adults have a pale yellow-brown, green-brown or dark brown head and thorax.
The potato aphid is quite restless and will drop when disturbed.
The potato aphid overwinters as nymph-producing females in sheltered sites, such as greenhouses and as eggs on rosaceous plants. The eggs hatch in the spring as the buds begin to swell. Two to six generations of females are produced on the overwintering host, during which time winged females mature and migrate to various weeds and to potato plants. Population build-up occurs at temperatures between 5 and 25EC. Aphid numbers continue to increase in July and winged forms are produced. By early or mid-August, the number of potato aphids on potato declines because winged males and females start to move to their overwintering hosts.
Wilting of the plants and honeydew on the leaves may be an indication of high numbers of potato aphids on the crop. Mainly flowers and shoots are attacked.
The potato aphid transmits potato virus Y on tobacco, but almost never on potato. It is also considered to be a poor vector of potato virus A and potato leafroll.
Monitoring - Abundance of the potato aphid is estimated by counting aphid numbers on leaves (see green peach aphid). In Eastern Canada, management is not necessary unless the potato aphid becomes sufficiently abundant to affect yields, which is why the empirical threshold is set fairly high. For example, in New Brunswick the threshold is 50 aphids per 3 compound leaves per plant and 40 to 60% of plants infested.
Chemical Control - Any recommended insecticide can be applied whenever sudden, rapid and significant increases in abundance of the potato aphid occur. However, chemical control of the potato aphid is only needed occasionally in Eastern Canada.