Asparagus is the only known food plant of this aphid.
Asparagus aphids feed in the axils of the modified leaves and under bracts. Heavily infested seedlings may form rosettes or shrivel and die. Similar infestations on older plants may cause severe dwarfing. Symptoms of aphid attack include a shortening of the internodes between the whorls of needles which produces a characteristic tufted appearance marked by a blue-gray color. Premature release of buds from the crown during the fern stage of growth can also occur. This can result in plant death if all viable buds are exhausted at the time of fern cutting. Feeding occurs only on the ferns, and aphid colonies have not been found on the marketable spears. In some areas of the U.S., this pest has been described as the most damaging species that feeds on asparagus.
The biology of this introduced aphid has not been studied in Oklahoma, but the following account is considered likely to occur here. Overwintering eggs are laid on the foliage in the fall and spend the winter on the plants or on the soil. Wingless females hatch in the spring and feed and reproduce on newly emerged asparagus plants. Several generations of both winged and wingless aphids are produced during the spring, summer, and early fall. Winged males are produced and mate with females as fall yellowing of the plants occurs and overwintering eggs are laid.
This is a small, slender aphid about 1/32 to 1/16 inch long. It is green to gray-green in color and is more or less covered with a gray, powdery material. The cornicles are very small and difficult to see without considerable magnification. The winged forms are darker, almost black, in color.
Please contact your local county extension office for current information.