Emerald Ash Borer
- Adult emerald ash borers are 1/4 to 1/2 inches long, narrow and bullet shaped with a flat back.
- Adults are metallic in color with purple/red metallic abdominal segments beneath their wing covers.
- Larvae can get up to 3 cm in length and are a creamy white color with no legs.
- Larvae body is made up of flattened, bell-shaped segments.
- Attacks all species of ash trees.
signs and symptoms
- Adult beetles emerge in late May/early June
- Bark splitting
- S-shaped tunnels behind outer bark
- D-shaped exit holes 1/8" wide on bark surface
- Woodpecker flecking
- Dead top branches of ash trees
- Leafy offshoots from the lower trunk of ash trees
- See image slideshow above for signs and symptoms
Emerald ash borer can be confused with many native insects. Check out these native look-alikes.
how to identify an ash tree
In Vermont, we have three species of ash trees: green ash (Fraxinus pennsylvanica), black ash (Fraxinus nigra), and white ash (Fraxinus americana). Here are some helpful links for ash tree identification:
- Ash Tree Identification, Michigan State University
- White Ash Tree Identification
- Green Ash Tree Identification
- Black Ash Tree Identification
Emerald ash borer (EAB), Agrilus planipennis, is an exotic beetle that was discovered in southeastern Michigan near Detroit in the summer of 2002. The larvae feed in the cambium between the bark and wood, producing S-shaped galleries that girdle and kill branches and trees. Emerald ash borer probably arrived in the United States on solid wood packing material carried in cargo ships or airplanes originating in its native Asia.
The EAB has one generation per year and goes through complete metamorphosis.
Adults lay eggs on the bark of the trunk or branches in the summer.
Eggs hatch in 7-10 days.
Larvae burrow into the tree and feed on the phloem and cambium layer, creating extensive galleries under the bark that disrupt translocation of water and nutrients in the tree. Galleries widen as larvae mature.
Pre-pupae larvae overwinter in shallow chambers in the outer sapwood or in the bark of thick-barked trees.
Pupation begins in late April or May.
Adults chew D-shaped exit holes are 3-4 mm wide.
Adults feed on the tree’s leaves between June and August.
Emerald ash borer has spread rapidly in the United States, killing millions of ash trees, and it will be in Vermont soon if it isn't here already. White ash is one of the ten most common tree species in Vermont, so this insect will have a major impact when it becomes established in the state. There are infestations in all surrounding states and Canadian provinces.
Emerald ash borer has not been detected in Vermont.
Taylor Scarr, Ontario Ministry of Natural Resources, Bugwood.org
Art Wagner, USDA - APHIS, Bugwood.org
David Cappaert, Michigan State University, Bugwood.org
Pennsylvania Department of Conservation and Natural Resources - Forestry Archive, Bugwood.org
USDA Forest Service - Northeastern Area, USDA Forest Service. Bugwood.org
Pennsylvania Department of Conservation and Natural Resources- Forestry, Bugwood.org