Emerald Ash Borer (Agrilus planipennis)

Key Identification Features

• Adult Insects

  • Bright metallic green carapace

    • Dorsal surface usually a bright red

  • Elongated & flattened body

• Infested Ash Trees

  • Small, D-shaped exit holes in Ash trees

  • Bark flecking and cracking in the upper branches of tree

  • Dropping of large branches

    • often shatter upon impact

Description

The effects of Emerald Ash Borers (EAB) are more commonly observed than the insects themselves, however, larvae, pupae, and adults can be found upon closer inspection. Ash trees infested with EAB often begin to drop large branches without notice that shatter when they hit the ground. Their bark begins to fleck and crack and when peeled away tunnels bored into the wood are apparent. When emerging EAB leave small, D-shaped holes in the wood. Leaves will begin to die back and discolor as EAB kill their host tree.

The larvae are larger than the adults, between 25-32mm in length when fully grown. They tend to be cream-colored with broad, flattened brown heads. Larvae have a 10-segmented abdomen and a fork-like appendage on the tip of the abdomen.

Pupae are between 10-15mm long and a creamy white color. As they mature they begin taking on the emerald colors of the adults. Once mature, they bore out of the wood leaving small D-shaped exit holes.

Adult EAB are bright, metallic green insects with elongated, flattened bodies. The underside of the elytra is typically bright red. Adults are between 8-14mm long and ~3mm wide. Adults feed on the leaves of their host trees through much of their lives and deposit their eggs between bark crevices or cracks in late June to early July.

Native Range

EAB are native to Asia and were likely first brought to North America in wooden packing material. EAB was first identified in SE Michigan in 2002 and is now found throughout much of the Eastern U.S. and Canada.

Habitat and Dispersion

EAB parasitizes native Ash trees (Fraxinus spp.) often resulting in the tree’s death within 2-4 years. Adults are capable of traveling 15km but their spread has been greatly aided by the movement of infected wood and trees.

Best Management Practices

EAB has become widely established in North America and eradication is unlikely at this point. Avoid moving wood out of infected areas and practice Buy it Where you Burn it. Infested trees can be cut down and burnt with caution, infested trees are fragile and can drop large branches without warning. Some studies using parasitic wasps are showing promise as biological control, but more research is needed.

Additional Resources

NYSDEC EAB Page

Invasive Species Center EAB Page

Emerald Ash Borer Network

USDA EAB Page

Don’t Move Firewood EAB Page