Emerald ash borer identification (vs lookalikes)

The emerald ash borer (Agrilus planipennis) has killed an estimated 100 million ash trees in North America since its discovery in Michigan in 2002. It is now established in at least 35 states and continues to spread. Accurate identification matters enormously -- both because ash trees worth.

The emerald ash borer (Agrilus planipennis) has killed an estimated 100 million ash trees in North America since its discovery in Michigan in 2002. It is now established in at least 35 states and continues to spread. Accurate identification matters enormously — both because ash trees worth treating deserve early diagnosis, and because misidentifying native ash borers or other common insects as EAB wastes money on unnecessary treatments and delays appropriate action.

I don't grow ash trees at my Long Island property, but the pest is established throughout the region, and I've seen EAB-killed ash trees on roadsides within a few miles. This guide draws on USDA APHIS, Penn State Extension, and Cornell Cooperative Extension research.

The pest

The emerald ash borer (Agrilus planipennis) is a jewel beetle (Buprestidae) native to Asia. Per USDA APHIS, it was first detected in North America near Detroit in 2002 and has spread to over 35 states and several Canadian provinces.

Adults:

• 7–15mm long, narrow, elongated
• Brilliant metallic emerald green
• Flat-bottomed when viewed from below (unlike the rounded body of most native metallic beetles)
• Red-purple abdominal segments visible under wing covers when resting

Larvae:

• Cream-colored, legless, S-shaped; 26–32mm at maturity
• Flattened head with bell-shaped first segment behind head
• Found in feeding galleries just under the bark

Host specificity: EAB infests only ash trees (Fraxinus spp.) with high reliability. Per Cornell Cooperative Extension, white fringe tree (Chionanthus virginicus) has also been documented as a host in rare cases.