Beech Scale Insect
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EmailDecember 19, 2025
In this video, Nate Walton, PhD, consumer horticulture educator for Michigan State University Extension, talks about beech scale insect (Xylococculus betulae). He also discusses the interaction between the scale insect and beech bark disease (Neonectria faginata and N. ditissima) and provides management options.
Video Transcript
I'm Nate Walton, MSU Extension and Consumer Horticulture Educator in Leelanau County. I'm here today at Wheelback Natural Area to show you an insect called beech scale. This kind of white, fluffy stuff you see on the bark of this beech tree is a scale insect. As you can see, it's kind of going all up and down the trunk, the lower portions of the trunk, although on a larger tree, you know, this is a fairly young beech tree. On a larger tree, you might see it going all the way up the trunk. The beech scale insect is certainly very unsightly, but it's not actually hurting the tree as much as you might think. This insect is more of a sign that the tree is infected with beech bark disease. Not all trees that have beech bark disease are going to show the scale insect, but what happens with beech bark disease is it weakens the tree, weakens its immune system. these trees do have an immune system that can fight off disease and fight off insect pests however with beach bark disease it's capable of weakening that immune system and the beach scale insect takes advantage of that and so you'll see trees in forests where there's a lot of beach bark disease a lot of beach trees will have really bad infestations of beach scale doesn't necessarily mean the tree is going to die beach bark disease doesn't kill all beach trees there are certain beach trees that have resistance to the disease and so those trees will remain standing although they might have beach scale insect infestations they can remain relatively healthy and and fight off the beach bark disease although if you look around this this forest has had probably the disease and the insect for more than 10 years i would say and many trees have died from the disease not all but many of the trees in this area are dead there are still some standing healthy trees however and and those trees will potentially drop seeds that will also give rise to resistant beech trees many of these areas where the disease moves through will lose a lot of trees quickly however again those remaining trees that are resistant will be able to hopefully reforest the area with resistant beech trees. If you have a tree like this in your yard with the beech scale insect there's certainly a chance that it won't won't die from beach bark disease so keep an eye on it. If you wanted to do something to kind of relieve the stress that's caused by the infestation of the insect you can scrub these off with just a sponge and soapy water and just scrub it with a scrub brush as high as you can reach uh you don't need to go all the way up the trunk you know no need to to uh get on a ladder or anything risky like that but just as high up as you can reach and that will um alleviate a little bit of the stress and strain on the tree we usually don't recommend using insecticides or fungicides or anything like that in this situation um scale has some uh natural enemies if you look but there are some little uh black uh pupae from ladybug ladybird beetles. It's the twice-stabbed ladybird beetle that loves eating these beech scale insects and you might see them among the scale insects during the growing season eating some of these scales. There are other insects like natural enemies like green lacewing that will eat the scale insect, brown lacewings, a variety of beneficial insects will come to these trees and play a part in helping to kill the scale insect so keep an eye on the trees and as long as they seem healthy probably doesn't don't need to do anything about this infestation if you do have concerns about the health of the tree certainly a good opportunity to contact a certified arborist and have them come and look and evaluate the tree's health.
