University of Maryland Extension

Plant Bugs - Trees

 plant bug damage
Damage to honey locust 

Key Points

  • Plant bugs are small sucking insects (2-9mm) that feed on the leaves of many shade trees including ash, oak, hickory, birch, honeylocust, and sycamore.
  • Plant bugs feed by piercing the leaves with their tube-shaped mouthparts, injecting an enzyme into the leaf tissue and sucking up the partially digested fluid.
  • Damage to leaves may appear as stipples (tiny white spots), small round holes and distorted leaves.

adult honeylocust plant bug
Honeylocust plant bug

Honeylocust Plant Bug

  • The honeylocust plant bug is pale green with wings held flat on the back.
  • Immature bugs look just like the adults, only smaller and with short wing bugs.
  • The immature plant bugs feed on emerging leaflets in spring causing them to become distorted with yellow blotches. Eventually, the distorted leaves (photo top of page) turn brown and fall off.
  • Adults appear around May and are gone by the end of June.  

Sycamore Plant Bug

  • Sycamore plant bug attacks sycamore throughout much of eastern North America.
  • Damage from this plant bug appears as small holes in the leaves and is generally not serious.


  • If large numbers of immature plant bugs are present at bud break, spray with a 1% horticultural oil.
  • If adults are abundant in June, spray with a 2% horticultural oil.
  • Trees will outgrow the damage if good growing conditions are present.
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