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Lettuce: Aphids

categories: Lettuce Lettuce Insects Vegetables

revision date: 2023-04-04 12:00

Aphid colony on leaf.
Aphid colony on leaf
Photo by: A.L. Antonelli

Biology

Aphids are small, soft-bodied, pear-shaped insects. They may vary in color from yellow to green to dark. Aphids typically feed in colonies on the leaves, often preferring the newer growth. Infested leaves turn yellow and may wilt or show other signs of water stress. Feeding aphids often produce large amounts of honeydew, a sweet, sticky material which may attract ants or become covered with a dark growth of sooty mold. The ants may protect aphid colonies from predators.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

  • Encourage natural enemies including ladybird beetles, lacewings, syrphid (hover) fly larvae, and parasitic wasps. Avoid use of broad-spectrum insecticides which kill beneficial insects.
  • Hand-wipe to help control small, localized infestations.
  • Wash aphids from plants with a strong stream of water. This may be ineffective on the low, dense foliage of lettuce.
  • Control honeydew-feeding ants.
  • Provide proper nutrition. High levels of nitrogen in the foliage encourage aphid reproduction. Switch to a slow-release or low-nitrogen fertilizer when practical.
  • Wash lettuce before eating.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

  • Follow label directions.
  • Apply when aphids first appear.

Approved Pesticides

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.

  • Safer Brand BioNEEM Multi-Purpose Insecticide and Repellent Concentrate [Organic]
    Active ingredient: azadirachtin [EPA registration number: 70051-6-42697]
  • Safer Brand Insect Killing Soap with Seaweed Extract II [Organic]
    Active ingredient: potassium salts of fatty acid [EPA registration number: 42697-59]
  • Surround At Home Crop Protectant
    Active ingredient: kaolin clay [EPA registration number: 61842-18-56872]
  • This list may not include all products registered for this use.

Additional Images