Integrated Pest Management

Locust Borer

Megacyllene robiniae

locust borer

Locust borer adult (Kevin D. Arvin,

locust borer larva

Locust borer larvae (Whitney Cranshaw, Colorado State University,

locust borer damage

Locust borer damage (Whitney Cranshaw, Colorado State University,

Pest Description

  • adults: 3/4 inch; black beetles with brilliant yellow markings
  • larvae: up to 1 inch long; white grubs without legs

Host Plants, Diet & Damage

  • black locust and its cultivars (e.g., purple robe locust)
  • feed on the xylem of host trees
  • extensive tunneling in the wood may cause structural weakness of branches or trunk

Biology, Life Cycle & Damaging Life Stage

  • overwinter as larvae in the bark
  • tunnel into and feed on heartwood in the spring and summer
  • adults emerge around August, mate and lay eggs on the bark
  • one generation per year
  • larvae are the damaging stage

IPM Recommendations

  • Manage trees to improve or maintain overall health.
  • Prune infested wood/branches and chip or burn.
  • Apply an insecticide (carbamate; pyrethroid) to the bark on the trunk and large scaffold branches in late-July/early-August prior to egg laying.

For more information, see our Locust Borer fact sheet.