Dying Arborvites #234628 - Ask Extension


Dying Arborvites #234628

Asked April 03, 2015, 5:59 PM EDT

I was told by an arborist that I have Japanese cedar longhorned beetles killing my trees. I have lost three already and two more are on their way out. He said he feels an insectice application will take care of it but reading your literature says there is no treatment. I don't want to spend money if it wont help but the infestation seems to be jumping from tree to tree.

Baltimore County Maryland

Expert Response

We would like to have more information and also view some photos of the trees and the damage. Submit photos of the whole tree and the site. Submit photos around the base of the trees and photos of the damage.
Also, you can clip out a shoot (a dying branch) at a time and look for evidence of the borer. The damage resembles winter dieback, so look carefully for oval exit holes about 4mm x 2mm. Peel back bark and look for tunnels. See our website for more information https://extension.umd.edu/hgic/invasives/japanese-cedar-longhorned-beetle

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