Emerald Ash Borer
Symptoms and Signs
The visual symptoms associated with emerald ash borer infestations are nearly identical to those we often see on ash that are infested or infected by other pests and diseases commonly found in Wisconsin. Therefore, it is important to look for a combination of at least 2 or more symptoms or signs (see list directly below) when trying to determine the presence of emerald ash borer. The following symptoms and signs are commonly associated with emerald ash borer infestations.
Symptoms
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- Crown dieback: Dieback of the upper and outer crown. Trees begin to show dead branches throughout the canopy, beginning at the top. Foliage in the top of the tree is thin and discolored. WDNR Photo by Jane Cummings Carlson
- Sprouting: Epicormic sprouting at the base and/or on the main stem of the tree. Trees may sucker excessively both at the base of the tree and on the trunk, often just below where the larvae are feeding. WDNR Photo by Renee Pinski
- Bark splits: Vertical splits in the bark are caused due to callus tissue that develops around larval galleries. Larval galleries can often be seen beneath splits. WDNR Photo by Linda Williams
- Woodpecker feeding: Woodpeckers feed on emerald ash borer larvae located under the bark. Feeding is typically evident higher in the tree where the emerald ash borer prefers to initially infest. WDNR Photo by Renee Pinski
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Signs
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- D-shaped emergence holes: As adults emerge from under the bark they create an emergence hole ~ 1/8 inch in diameter and D-shaped. WDNR Photo by Renee Pinski
- S-shaped larval galleries: As larvae feed under the bark they wind back and forth, thus creating galleries that are packed with frass and sawdust and follow a serpentine pattern. WDNR Photos by Linda Williams
- Larvae: Larvae are cream-colored, dorso-ventrally flattened and have pincher-like appendages (urogomphi) at the end of their abdomen. Mature larvae reach 11/2 inches in length and all larvae are found feeding beneath the bark. WDNR Photos by Linda Williams
- Adults: Adult beetles are metallic green in color and are 3/8 - 1/2 inch in length and 1/16 inch in width. Adults are dorsally flattened and ventrally rounded. WDNR Photo by Renee Pinski
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 at the end of their abdomen. Mature larvae reach 11/2 inches in length and all larvae are found feeding beneath the bark. WDNR Photos by Linda Williams',600,600,1,0))
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Last Revised: Wednesday March 05 2008
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