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Many different kinds of beetles feed on ornamental trees and shrubs in either the adult or larval stages. Since there are more beetles in the world than any other kind of insect, it stands to reason that many of them will be ornamental pests. Here we will show a few representatives that are common to Idaho.

  Elm leaf beetle adult

Elm leaf beetle adults overwinter in protected places and feed on developing elm leaves. After feeding for a while they lay clusters of small yellow eggs.

  Elm leaf beetle larvae and damage

Most of the feeding damage to elms is caused by the larvae. They skeletonize the leaves. A tree can be weakened if allowed to be defoliated several years in a row.

  Cottonwood leaf beetle adult

Similar to the elm leaf beetle, the cottonwood leaf beetle feeds on willows, cottonwood, and other poplars. It also belongs to the leaf beetle family.

  Cottonwood leaf beetle larva

The larva of cottonwood leaf beetle are black when young and become dirty yellow as they mature.

  White pine weevil adult

White pine weevils attack pine and spruce trees in Idaho landscapes. The adults overwinter and start laying eggs in the previous year’s leader. Timing sprays to kill adults before they lay eggs is the only practical control method at present.

  White pine weevil larva

White pine weevil larvae are legless grubs that develop in the trees. They feed all summer, pupate and pupate in the tree.

  White pine weevil damage

Trees infested with white pine weevil develop crooked and dying leaders and some loss of side shoots also.

  Black vine weevil adult

Black vine weevil adults overwinter in protected places and are common nuisances in houses. As new adults emerge, they feed on peony, lilac, and other shrubs causing a charaecteristic notching along the edge of the leaves.

  Notching of leaves by black vine weevil adults

  Black vine weevil larva

Larvae of black vine weevil feed underground on root of shrubs and trees.

  Blister beetle adult

Blister beetles are general feeders on plant foliage. They are beneficial in that the larvae feed on grasshopper eggs. They secrete a fluid that can cause minor blisters on the skin.

  Flea beetle adult

Early in the year flea beetles are the first insects to start chewing holes in the leaves of our annuals or early emerging perennials. They are either black or metallic green or blue. They have jumping legs and readily disappear when approached. They make very small round holes in the leave where they feed.

   Milkweed beetle adult

Occasionally these milkweed beetle adults will be found feeding on yard plants. They mostly prefer milkweed plants. They can be metallic green to dark blue.

  Rose curculio adult

Rose curculio adults are red, red and black, or black. They feed and lay eggs in rose buds and hips. The larvae are small c-shaped legless grubs that feed on the seeds.