University of Maryland Extension

Leaf Beetles - Trees

leaf beetles
The imported willow leaf beetle

Key Points

  • Leaf beetles feed on the foliage of plants as adults, larvae or both.
  • Feeding by the adults appears as holes eaten through the leaf or skeletonization of the lower side of the leaf.
  • Larvae may feed on the surface of the leaf or mine the leaves depending on the species.
  • This is a large group of beetles and there is great variation in size and color.
  • The adults are small to medium sized, and some are metallic.
  • Larvae are usually soft-bodied and vary greatly in shape depending on their feeding habits.
  • Some common examples of leaf beetles are the locust leaf miner, elm leaf beetle, cottonwood leaf beetle, and imported willow leaf beetle.

locust leafminer and damage
Locust leafminer adult and damage on black locust

  • The locust leafminer feeds primarily on black locust. The larvae feed inside and cause blotch mines. In heavy infestations the mines may coalesce and turn the leaves brown. The adults skeletonize the leaf surfaces between small veins. Black locust is tolerant to this pest and control is not recommended. Use good cultural practices that promote tree vigor.

cottonwood leaf beetle and damage
Cottonwood leaf beetle adults and larva.

  • The cottonwood leaf beetle feeds primarily on cottonwood, but will attack other species of poplar and willows. Larvae skeletonize leaves between the leaf veins. Adult feeding causes irregular shot holes. In heavy infestations tender terminals may be defoliated. Treatment is rarely necessary. 
  • The imported willow leaf beetle (photo at top of page) feeds on several varieties of willow and cottonwood. The larvae feed in groups and skeletonize the lower surface of older leaves. Adults chew holes in young leaves. If needed, the control is the same as for cottonwood leaf beetle. In wet summers, willows continue to grow and usually mask the damage, making sprays unnecessary.

Additional Resources 

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