The asparagus aphid was brought over from Europe as recently as 1969. It is primarily a pest in the arid Northwest, but can occasionally be a minor problem in the Northeast as well. It will infest cultivated, wild, and ornamental asparagus. These are small, oval, green to gray aphids that may be covered in a waxy secretion. The cornicles (tail pipe-like projections) are small and inconspicuous.
Life Cycle: Males and female adults are produced in September and October and will mate and lay eggs on the lower portion of the ferns. Eggs hatch in the spring, go through 4 nymphal instars and then develop into stem mothers: capable of producing up to 55 live female nymphs within 20 days. The nymphs mature in 8-10 days and begin to produce the next generation of female nymphs soon after. In the spring, some adult females have wings and will disperse to new hosts.
Damage: Aphid feeding causes a shortening of the internodes and a rosetting or brush-like appearance of the foliage, especially near the tips of the lower branches. High aphid populations will reduce plant vigor and yield or kill seedlings. A combination of infestations and cold winters can kill even full size crowns within two years.
Monitoring: Watch for abnormal plant growth on the lower portion of the fern.
Cultural, Biological and Chemical Management: A combination of removing dead ferns during the fall or winter, and spring tillage will usually control this pest. There are many natural enemies that help keep the aphid populations in check during the season including; lady beetles, lacewings, predatory midges, flower fly larvae, the Braconid wasp Diaeretiella rapea, and parasitic fungi. Treating the ferns twice, about 10 days apart, with a systemic insecticide (i.e. dimethoate) will also provide effective control.
By: T. Jude Boucher, University of Connecticut, Cooperative Extension System
January 2005, Reviewed 2012
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