Potato Aphid
Macrosiphum euphorbiae (Thomas), Aphididae, HEMIPTERA


DESCRIPTION

Adult - This soft-bodied, pear-shaped insect may be solid pink, green and pink mottled, or light green with a dark stripe. Usually wingless, it is about 2.5 to 3.5 mm long and has a pair of long, slender tailpipe-like appendages known as cornicles.

Egg - The egg stage does not occur in North Carolina.

Nymph - Although slightly smaller than the adult, the nymph is similar in color and shape.


BIOLOGY

Distribution - Potato aphids occur throughout North America.

Host Plants - Potato aphids infest a wide range of host plants. Some important cultivated hosts include potato, tomato, eggplant, sunflower, pepper, pea, bean, apple, turnip, corn, sweet potato, asparagus, clover, and rose. Weeds such as ragweed, lambsquarters, jimsonweed, pigweed, shepherdspurse, and wild lettuce are also common food plants.

Damage - Sporadic in occurrence, potato aphid infestations are rarely severe enough to kill plants. Aphids pierce veins, stems, growing tips, and blossoms with their needle-like mouthparts. As a result, blossoms are shed and yield is reduced. New growth becomes stunted and curled. Heavily infested plants turn brown and die from the top down. Aphids tend to spread rapidly from field to field transmitting a number of viral diseases. These include various mosaics, leaf roll, spindle tuber, and unmottled curly dwarf.

Life History - In North Carolina, female potato aphids feed and reproduce year round. No eggs or males are produced. Without mating, wingless females give birth to about 50 live nymphs. During warm weather, each of these nymphs matures in 2 or 3 weeks. The life cycle continues in this manner until overcrowding occurs or food becomes scarce. At these times nymphs develop into winged adults and migrate to new host plants. Once settled down, these aphids begin reproducing and the life cycle continues as before. During winter, however, feeding and reproduction occur at a much slower rate. Many generations are produced each year.


CONTROL

Lady beetles and their larvae, lacewing larvae, syrphid larvae, and stilt bugs all feed on aphids. Fungus diseases, high temperatures, damp weather, and hard rains also limit aphid populations.

Cultural practices are helpful in avoiding aphid populations. Crops should be planted in well-prepared, fertile seedbeds to promote vigorous growth. When possible, avoid planting sites near infested fields or from which an aphid-infested crop has been removed.

A number of insecticides are available to control aphids on a wide variety of crops. However, repeated applications of certain carbamate insecticides within intervals of a week or less are frequently conducive to aphid buildups. For specific chemical recommendations, consult the current North Carolina Agricultural Chemical Manual.

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