Elm leaf beetle
Eggs are orange-yellow and spindleshaped. Larvae are small, black, and grublike. At maturity larvae are approximately 13 mm long, dull yellow, and with what appears to be two black stripes down the back. Adults are about 6 mm long, yellowish to olive green with a black stripe along the outer edge of each front win.
Damage: Injury caused by this pest may result in partial or complete defoliation of trees. Heavily infested foliage will turn brown and often drops prematurely. In some cases by mid-summer an entire tree may be defoliated. The majority of damage is caused by larvae feeding on the lower leaf surface. Trees that lose foliage as a result of heavy damage by this pest commonly produce a new flush of growth that may be consumed by the remaining insects found on the host tree. Hibernating adults in homes do not cause structural damage but may be a nuisance.
Feeding damage by this key pest seldom kills an elm tree. Severe defoliation may weaken a tree, making it more susceptible to attack by other insects and diseases such as Dutch elm disease. This pest does not carry Dutch elm disease, but the smaller European elm bark beetle, Scolytus multistriatus , and the native elm bark beetle, Hylurgopinus rufipes , that attack weakened trees, do. Even without secondary attack by other insects and diseases, repeated attacks by the elm leaf beetle may eventually weaken trees to the point of death.
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