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Common Insects & Mites

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Caption: Aphid colony

Photo by: Unknown

Common Insects & Mites : Aphids

(revision date: 4/30/2013)

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

Biology

Many species of aphids attack ornamental plants. Some are fairly host-specific, while others may attack a dozen or more different host species. In some cases, aphids may only withdraw nutrients and moisture with their sucking mouthparts, causing no real damage when their populations are small. Others secrete "toxins" in their saliva while feeding, causing various deformations, even when their numbers are low. Feeding aphids excrete "honeydew," a sweet, sticky, shiny substance which accumulates on leaves or other surfaces. Honeydew serves as a nutritious food source for development of black sooty mold fungi and is attractive to honeydew-feeding insects such as ants. As aphids grow, they shed their "skins" or part of their exoskeleton like other insects. Cast skins serve as signs of current or past aphid presence. Many species of aphids prefer lush, tender new shoots and leaves, while others feed on the top or bottom surfaces of leaves, on stems, or on branches.

Management Options

Non-Chemical Management

Various predators, such as lacewing larvae, ladybird beetle adults and larvae, syrphid fly maggots, soldier beetles, and certain midges, help manage aphids. Some of these predators can be purchased by home gardeners.
Apply a fairly strong stream of water to the plant. Use care that the water stream does not damage flowers or young leaves.
Hand-wipe or prune to control small, localized infestations (when practical).
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

If nonchemical management options do not give satisfactory control, several insecticides are effective in managing aphids. However, the insecticide must be registered for the host plant. Find a list of registered pesticides for a specific host by referring to the fact sheet for aphids on that host.

Images

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Caption: Aphid colony Photo by: Unknown
Caption: Aphid cast skins Photo by: R.S. Byther
Caption: Lily aphids Photo by: R.S. Byther
Caption: Green peach aphid Photo by: Unknown
Caption: Aphid colony Photo by: R.S. Byther
Caption: Aphid colony Photo by: R.S. Byther
Caption: Aphid colony Photo by: A.L. Antonelli

WSU Extension

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