Elm: Elm leaf beetle
categories: Elm Elm Insects Ornamental trees Ornamentals
revision date: 2023-04-04 12:00
Photo by: Unknown
Biology
Elm leaf beetles feed on the leaves both as larvae and as adults. The larvae appear in late spring (typically May-June) from eggs laid by overwintering adults. The 1/4″ larvae are greenish or yellow with black stripes and spots. They skeletonize leaves, feeding on the underside and eating all parts except the veins and upper cuticle, which turn brown. Adult elm leaf beetles are approximately 1/4″ long and yellow to greenish with two dark stripes. Older adults are darker. Adult feeding causes small holes in the leaves. Severe infestations may result in severe premature leaf loss. Trees may releaf in late summer. Repeated infestations may weaken or kill trees. Weakened trees are also more susceptible to attack by elm bark beetles, which can carry the Dutch elm disease fungus.
Management Options
Use Integrated Pest Management (IPM) for successful plant problem management.
Non-chemical Management
Select non-chemical management options as your first choice!
- Plant resistant cultivars of American elm (Ulmus americana) including ‘Dynasty’, ‘Princeton’, ‘Prospector’, ‘Frontier’, and ‘Pathfinder’ (NOTE: Many American elm cultivars are highly susceptible to Dutch elm disease.)
- Other elms reported to be somewhat resistant to elm leaf beetle feeding include Chinese (U. parvifolia) and the elm-like zelkovas (Zelkova spp.)
- Provide proper culture to maintain plant health. Healthy plants are more tolerant of insect damage.
- Prune dead and dying branches in late fall or winter.
Chemical Management
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
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Apply when first larval damage appears.
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Homeowners should not make foliar applications to trees over 10 ft tall.
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Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.
Approved Pesticides
Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.