Bark beetle treatment?


New Member
Anybody have any experience with treating bark beetles? I've been using a bifenthrin trunk spray preventatively, but wondering if there's anything to be done if the tree may have already been exposed? I know it's not a terribly clear photo, but somebody I work with took this thinking it could be frass. We've proposed this preventative bark spray to the client but I'd hate to see this otherwise healthy old willow oak suffer from insects that may already be affecting the tree.

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Well-Known Member
The very fine frass appears to be ambrosia beetles damage. Immediately left of that appears to be Formosan termite tunnels. Both are bad news. Get in touch with a local certified arborist with plant health care experience for more accurate information and possible treatment options.


Well-Known Member
Ambrosia beetles, and true bark beetles, are generally attracted to stressed trees. Here, ethylene has been implicated in attracting ambrosia beetles, especially in waterlogged conditions in spring.

Look for the stress agents at play too.


Well-Known Member
It's an impressive willow oak. I didn't measure but it's probably more than 55" dbh. No recent soil disturbance nor heavy pruning, but it's in a residential area around a other mature willow oaks planted along the streets. A number of the others willow oaks showing signs of stress and the city is removing them one by one. Except for that bit of frass in the one location, this one tree looks to be in great condition. But I am imagining ambrosia beetles feeding and multiplying right now just under the bark.

For trunk sprays I know of BifenXTS (bifenthrin) and Safari 20SG (dinotefuran). I gather that the bifenthrin won't touch the critters under the bark. Safari isn't labeled for ambrosia beetle specifically, but I don't see why it wouldn't kill them and it's supposed to penetrate the bark and act systemically in a tree (and maybe Pentrabark would help?). Are there other trunk sprays we should look into? Would injections be better?
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Well-Known Member
I don't believe the neonics have any labeling for bark beetles but would be far less expensive than em ben which does.

If there is a plan to address cultural problems now and in the future, than a strong em ben injection may be warranted.


Well-Known Member
I appreciate the feedback and I will make a closer investigation next time I'm up there (might be a couple weeks). What do you guys do for termites in trees?


Well-Known Member
Call the exterminator. I don't want to termites in the house to end up pinned on me.

For carpenter ants, sevin dust sprinkled around where they frequent does a good job.


Well-Known Member
oldoak it would be a shock to me if Formosans are in upstate NC.

Nish, when you go back, cautiously pull off the dead bark and you will get a lot more info.

Note the problems are in a sinus with vascular issues, so it seems doubtful the whole tree will be affected.

Stephen Moore

Well-Known Member
You say the city has been systematically removing infected trees? Have they died or were they actively infested? The reason I ask, is Beatles need a home, obviously, so when large amounts of houses are removed it increases the population in the remaining trees. The reverse is also true, as in the pine beetle here in BC. The numbers spiked due to warmer winters and they infested pine across the province. Huge swathes of trees were internally girdled and they died in months by the millions. The beetles literally ate themselves out of home. Now the population has stabilized despite the fact the winters are still warmer than usual because they have far fewer homes to breed in.