Common Insects and Mites: Spider mites

Biology

Several species of spider mites may become significant pests on ornamental plants. Spider mites are very small, eight-legged arthropods that damage foliage with their piercing mouth parts. They are usually found on the undersides of leaves. Strands or mats of silk webbing may be present on the underside of infested leaves or in the axil between leaf and stem. Cast skins, eggs, eggshells, and living mites are all commonly present in the webbing. Mite damage begins as a fine yellow or bronze stippling or speckling of leaves. Large infestations may result in overall yellowing or bronzing of affected foliage. Severely damaged leaves may drop from the plant. Hot, dry conditions and high levels of nitrogen in the leaves favor mite infestations.

Management Options

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

Non-chemical Management

Select non-chemical management options as your first choice!

• High levels of nitrogen in the foliage encourage spider mite reproduction. Switch to a slow-release or low-nitrogen fertilizer when practical.
• Hose mites from plants with a strong stream of water.
• Predatory mites and insects such as ladybird beetles and green lacewings aid in control of mite populations. Avoid use of broad-spectrum insecticides which kill beneficials.
• Provide proper culture. Healthy plants are more tolerant of damage, while drought-stressed plants are more susceptible.

Chemical Management

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

If nonchemical management options do not give satisfactory control, insecticides may be effective in managing mite populations. 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 spider mites on that host.

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