Aphids are small, pear-shaped, soft-bodied insects. They may range in color from yellowish to a waxy gray-green. Aphids typically feed on the underside of leaves, in buds, or in heads of broccoli or cauliflower. Aphid feeding can cause foliage to yellow. Wilting or stunting of plants may occur if infestations are severe. Aphid feeding produces honeydew, a sweet, sticky material which may attract ants or become covered with a dark growth of sooty mold. Some species can overwinter as eggs on plant debris.

Management Options

Non-Chemical Management

Remove plant debris from the garden in the fall.
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 control small, localized infestations.
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.

Select non-chemical management options as your first choice!

Chemical Management

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

Apply when aphids first appear. Repeat at 8- to 10-day intervals. Do not apply unless leaves are dry. Thorough coverage of the foliage is important, including lower leaf surfaces. A surfactant (spreader) may need to be added to some products. Read the product label for timing between last application and harvest. Insecticidal soaps may require more than one application.

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 with Seaweed Extract II [Organic]
Active ingredient: potassium laurate | EPA reg no: 42697-59
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: Aphids on kale Photo by: C.A. Miles
Caption: Aphid cast skins Photo by: R.S. Byther
Caption: Aphid colony Photo by: Unknown

WSU Extension

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