I have read that only a paint or varnish layer will do the trick, but I'm wondering if there's any oil-based penetrating sealant for cedar that has some ingredient carpenter bees find noxious, so I can discourage them from chewing up my siding and trim. Last summer was really bad, and today they're back.


They're are insecticides that will keep these flying drill bits from nesting in your eaves. The ones I know of need to be applied by a pro but seem to be good for multiple years.

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  • Thanks. I have to look into whether the application is a coating, or a spray that could get carried on the air onto shrubs. – user41524 Apr 1 '16 at 17:53

I too have had this problem... adding a lavender bush next to house with pine siding is asking for trouble.

But to answer your question, yes and no. Regarding noxious, the solvents (in the varnish) will repell the bees for a short while (the first year perhaps). But to be sure, it won't keep the bees out indefinitely. edit- I think that you would have to deep seal it with shellac, then perhaps epoxy over that, which should pretty much blow your budget. Borates are the most common wood treatment (before you varnish). You can also use carbaryl (sevin) for short term fix (every summer) after you varnish.

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  • 2
    A side note- the toxicity of carbaryl toward bees is so high, manufacturers don't like to mention it, on account of issues with honey bees. – Ben Welborn Apr 1 '16 at 15:46
  • Thanks for the caveat. ct.gov/deep/lib/deep/pesticide_certification/Supervisor/… – user41524 Apr 1 '16 at 17:52
  • Carpenter bees have a similar level of sensitivity, and since honey bees don't really spend much time on houses, carbaryl is a good choice for dealing with carpenter bees. The only drawback is that carbaryl only lasts for about 2 weeks. – Ben Welborn Apr 1 '16 at 18:20

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