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Emerald Ash Borer
Order: Coleoptera
Family: Buprestidae
Scientific name: Agrilus planipennis Fairmaire
Common name: Emerald ash borer (EAB)

Identification of EAB signs and symptoms:
  1. Canopy dieback. Look for dying limbs or branches in ashes. Dieback usually occurs in the upper one third of the canopy. Since beetle activity is normally initiated in the canopy and other signs or symptoms may be hidden from view, this sign can be very useful.
  2. Adult beetle emergence holes. Look for D-shaped exit holes, 3 to 4mm in diameter, on the branches or trunk. Attack is initiated at the top of the canopy, so emergence holes may not be visible low on the tree during the early attack phase.
  3. Suckering. Look for a proliferation of sprouts directly from the trunk or main branches. Suckering is a handy secondary symptom of infestation because it is easy to see even when emergence holes are too high to observe.
  4. Bark splitting. Look for cracked or vertically split bark resulting from a tree’s defensive response to EAB infestation
  5. Galleries. If an infected tree has been heavily infested for a prolonged period, you may be able to pull back dead bark to reveal EAB larval feeding galleries or tunnels. These are much more meandering and serpentine than those of many other wood boring insects. The galleries are pale, curving lines on the exposed sapwood, up to about 8 mm thick (the width of a pencil).
  6. The adult beetle. It is unlikely that adults will be seen, except in very heavy infestations. Adults are shiny, metallic green, narrow beetles with parallel sides. They are about 9 mm (3/8 of an inch) long. They can be found on the bark, especially in crevices, from mid-May to late June. From June through July, adults are more likely to be feeding on leaves (particularly in the canopy).
emerald ash borer adult
eab larval galleries
emerald ash borer larva

Damage: EAB larvae are wood borers and feed in the inner bark of ash trees, disrupting the trees ability to transport water and nutrients. It takes 1 to 3 years for an infested tree to die.
Impacts: EAB are wood borers that attack true ashes (Fraxinus spp.) and cause 100% mortality of infested trees. Ash trees are one of the most common landscape trees planted in the US. EAB in Oregon would be devastating to native ash trees, landscape ash trees, and the nursery industry. EAB has the potential to eliminate all ash trees from North America.

Host plants: The Emerald Ash Borer has a narrow host range which includes all species of ash trees. Mountain Ash is not a true ash and is not a host. EAB attacks both healthy and stressed trees.
Distribution: There are infestations in Indiana, Maryland, Michigan, Illinois, and Ohio. Some of these infestations are currently being eradicated.
distribution maps

Biology and Life Cycle: In temperate regions such as Oregon, EAB has a one-year life cycle. The insect overwinters in ash trees as full grown larvae. Pupation begins in late April and adult beetles begin to emerge from their D-shaped exit holes in early June. Feeding and mating take place from June to early August. Eggs are then oviposited into ash bark crevices and the adults die. The eggs hatch and the immature larvae feed and grow in the bark cambium, creating S-shaped galleries. The larvae are full grown in time for winter.

How you can help:
If you see this beetle or find ash trees with signs of damage, please:

  • Note the date and location where you found the beetle or damaged tree.
  • Capture the beetle and place it in a jar in the freezer to kill it and store the dead beetle.
  • Immediately report the information by calling the Oregon Department of Agriculture at: (503) 986-4636 or 1-800-525-0137.

What ODA is doing: Each year ODA visually surveys more than a thousand ash trees across the state. In 2007, the ODA initiated a pilot trap tree survey. Forty specially prepared ash trees have been planted at twelve sites in the Portland area. These surveys allow the ODA to detect any infestations when they are relatively small and more easily eliminated.  The ODA also promotes the use of locally harvested firewood, a recognized pathway of emerald ash borer. 
USDA National Invasive Species Information Center
EAB info.
Don’t move firewood

Photo credits:
EAB adult:David Cappaert, www.forestryimages.org
EAB larval galleries: Michigan Department of Agriculture, www.forestryimages.org
EAB larva: David Cappaert, www.forestryimages.org