Thursday, December 1, 2016

Finding EAB in Winter

Stripping of ash bark by woodpeckers while seeking emerald ash borer larvae; this foraging damage is called “blonding.” Photo: Jennifer Forman Orth,MDAR
The Missouri Department of Conservation is looking for help from birdwatchers, hunters and others of us out in the woods in watching for signs of Emerald Ash Borer (EAB).  EAB kills ash trees in the genus Fraxinus, which includes the commonly planted green ash and white ash.  It has been reported in 30 Missouri counties but none reported in Southwest Missouri so far.

You may have seen photographs of the typical small D-shaped hole the insect produces.  More dramatic are the tracks under the bark after the tree is dead.  Since EAB usually starts high up in the tree, these finds are hard to see.  Robbie Doerhoff, Forest Entomologist with MDC shared some more signs for bird watchers and other of us out in the woods to be looking for including "bark blonding," a new finding to me.  To quote Robbie:
"So, what is bark blonding? Woodpeckers searching for insect larvae inside trees often pop off the outer bark (see EAB website). On ash trees, this feeding activity reveals a white inner bark that is highly noticeable. Ash trees with bark blonding may not have EAB, but it is certainly worth reporting these trees for a closer look by trained foresters."

Ash bark blonding (L)

Woodpecker damage with blonding (R)

Ash bark - click to enlarge
However, first you need to be able to identify an ash tree, a little harder with the leaves off this time of year.  Look for gray to brown bark with interlacing corky ridges forming obvious diamonds.  Another clue, useful when looking for morels in the spring, is looking for trunks that split into two main branches10-20 feet above the ground.  Finally, look at the branches.  Ash tree branches are opposite like maple trees but with this more distinctive bark.

The Birdwatcher's Guide to Holes in Trees has more pictures and information.  If you find suspicious signs on an ash tree, report the tree locations using the online form at They are most interested in reports from new counties where EAB has not yet been found as shown on the map below.