Emerald Ash Borer
Emerald ash borer larva (Pennsylvania Department of Conservation and Natural Resources, Bugwood.org)
* This pest does not currently occur in Utah.
- adults: 1/2 – 3/4 inch; slender; emerald green with purple body under wings
- larvae: creamy white with an enlarged head area; tapeworm-like appearance
Host Plants, Diet & Damage
- feed on all ash trees
- infestations initially occur in the top third of the canopy
- later, beetles infest the main trunk
- feed on phloem and etch sapwood of main trunk or branches
- create serpentine galleries under the bark
- cracked bark; epicormic branching; woodpecker feeding
- leave diagnostic, D-shaped exit holes in bark
- cause canopy dieback and complete tree death
Biology, Life Cycle & Damaging Life Stage
- overwinter as larvae in the sapwood
- adults present late-May through August
- eggs laid on bark or in bark crevices
- one generation per year
- prefer stressed, weakened trees
- similar-looking beetles (Agrilus spp.) occur on other, non-ash trees in Utah
larvae are the primary damaging stage
- Monitor all ash trees for canopy dieback, water sprouts, woodpecker damage, serpentine, frass-packed galleries under the bark and D-shaped exit holes.
- Report suspicious ash trees or insects here.
For more information, view our Emerald Ash Borer fact sheet.