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Watch for signs of tree-killing pests

By Mary Beth Breckenridge Published: August 13, 2013

Ohio is trying to stop the march of two tree-destroying insects, the walnut twig beetle and the Asian longhorned beetle.

That’s why it’s urging Ohioans to check their trees this month for signs of the insects. August is when symptoms of invasions by both pests are visible.

Although both beetles have been detected in southwestern Ohio, they’re not known to have reached our area yet. The state Department of Agriculture hopes vigilance will keep that from happening.

The walnut twig beetle is a yellowish-brown insect that’s tiny, less than one-tenth of an inch long. It carries a fungus that causes thousand cankers disease, which can kill walnut trees.

The twig beetles bore into branches and tree trunks, introducing the fungus. There is no known treatment for the disease, the agriculture department says.

To tell whether your walnut tree has been attacked, watch for a thinning crown, yellowing or wilted leaves and newly dead limbs.

The Asian longhorned beetle is a large, shiny black insect with random white spots. It’s 1 to 1-1/2 inches long, not including its white-banded antennae. Those antennae can be as long as the body on females and almost twice as long on males.

The longhorned beetle attacks up to 13 kinds of trees, including maple, birch, horse chestnut, poplar, willow, elm, ash and buckeye.

Signs of infestation by the Asian longhorned beetle include perfectly round exit holes about 3/8 to ½ inch wide, made by adult beetles when they emerge from the trees; pock marks on trunks and branches where females deposit eggs; frass (wood shavings and sawdust) produced by larvae feeding and tunneling; early fall coloration of leaves or dead branches; and running sap produced by the tree at the egg-laying sites. Infested wood may also break during high winds.

If you suspect damage from either of the beetles, call 855-252-6450 or email If you can snap a photo of the insect on your smart phone, you can submit it for verification to the Great Lakes Early Detection Network using its app.



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