Introduced Pests Outreach Project

Emerald Ash Borer

(Click on an image below to see the captioned full-size version)
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Scientific Name: Agrilus planipennis
Common Name: Emerald Ash Borer, "EAB"

Known Hosts:
White ash (Fraxinus americana), black ash (F.nigra), red ash (F. pennslyvanica), green ash (F. pennsylvanica var. subintegerrima) and several horticultural varieties of ash.

Key ID Features (Adults, Larvae):
  • The body is a golden green or brassy color overall with darker, metallic emerald green wing covers. (Figure 1)
  • Adults measure ½” 8.5-13mm) in length. Females are larger than males. (Figure 2)
  • Adults are present from mid May to late July and feed on leaves leaving irregularly- shaped patches with jagged edges.
  • Larvae are flattened in appearance, consisting of 10 cream-colored, bell-shaped segments with a pair of brown pinchers at one end. (Figure 3)
  • Larvae about 1-1 ¼” (26- 32mm) in length when fully developed.(Figure 3)
Description of damage:
  • Distinct S-shaped tunnels are formed beneath the bark from larval feeding. (Figure 4)
  • Vertical splits in the bark are caused by callus tissue forming in response to larval feeding. (Figure 5)
  • Adult emergence leaves D- shaped exit holes (3-4 mm in diameter) in bark. (Figure 6)
  • The upper third of the tree dies back.
  • Numerous shoots arise below the dead portion of the trunk (Figure 7)
Similar Species:
  • The emerald ash borer is larger and a brighter green than any of the native Agrilus species.
  • Six-spotted tiger beetles are ground beetles that are very bright metallic green, but are larger than EAB and have a distinctively different, more rounded body shape.
  • The two-lined chestnut borer (Agrilus bilineatus) and bronze birch borer (Agrilus anxius) are similar in shape but are not green. They attack oak and birch trees, respectively.
  • Other bright green insect sometimes confused with EAB in Massachusetts include cuckoo wasps, sweat bees, and Dichelonyx beetles.

last updated February 18, 2021

Massachusetts Department of Agricultural Resources
The Massachusetts Introduced Pests Outreach Project is maintained by staff at the Massachusetts Dept. of Agricultural Resources. This website was made possible, in part, by a Cooperative Agreement from the United States Department of Agriculture's Animal and Plant Health Inspection Service (USDA APHIS). It may not necessarily express APHIS' views.