WSU Extension

Hortsense

Bean : Bean aphids
(revision date: 3/10/2017)


Biology
Bean aphids are small, pear-shaped, dark green to black insects. These soft-bodied insects often feed in clusters on the shoot tips and leaves of new growth. Severe infestations can result in curled or deformed leaves and shoot tips. Aphid feeding can produce large amounts of honeydew, a sweet, sticky material that may attract ants or become covered with a dark growth of sooty mold. The summer form of the aphids may be found on various hosts including many vegetables, flowers, and ornamentals. The aphids typically overwinter on hosts such as euonymus and viburnum.
Management Options

Non-Chemical Management
  • Encourage natural predators including ladybird beetles, lacewings, syrphid (hover) fly larvae, and parasitic wasps. Avoid use of broad-spectrum insecticides which kill beneficial insects.
  • Hand-wipe or prune to control small, localized infestations (when practical).
  • Wash aphids from plants with a strong stream of water.
  • Control honeydew-feeding ants, which may protect aphid colonies from predators.
  • Provide proper nutrition. High levels of nitrogen encourage aphid reproduction. Switch to a slow-release or low-nitrogen fertilizer if necessary.
Select non-chemical management options as your first choice!

Chemical Management

Apply when aphids first appear.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Safer Brand BioNEEM Multi-Purpose Insecticide & Repellent Conc [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 70051-6-42697
  • Safer Brand Insect Killing Soap Conc II [Organic]
    Active ingredient: potassium laurate  |  EPA reg no: 42697-60
  • Surround At Home Crop Protectant
    Active ingredient: kaolin clay  |  EPA reg no: 61842-18-56872
  • This list may not include all products registered for this use.
Images
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Caption: Bean aphid
Photo by: K. Grey