As I posted in another question, I had wasps entering my fireplace exhaust in my backyard. When I turned the fireplace on, I got a distinct burning smell; and then it went away.

Then I saw them crawling into a small space between two bricks in my front overhang. So I sealed it up with silicon. The next day, I saw a dead wasp there.

Now, I have a feeling (not 100% sure) that I saw a wasp fly into that front overhang area, and not fly out. I'm concerned that there's a wasp nest, and that they're not dead yet.

How can I find out for sure? Do I need to call a professional? (I looked everywhere in my house, but I couldn't find any signs of them.)

And, how do I find their new entrance to the nest, if there is one and there is a nest?

2 Answers 2


I would buy a lot of wasp spray and and spray it all around the overhang area. You might eventually start seeing dead wasps in one general area and be able to find the entrance that way. Of course, you may need to wait until summer since it's winter time now.


Unless you've gotten the nest, no they're not. First question, are they the long waisted Paper Wasps or Yellow Jackets? Second, was the hole they were coming out of under the sheet metal trim collar that surrounds the vent and joins to the wall or out of the vent itself?

If it was the vent itself, these usually are a concentric system where there's air insulation/intake and a center hot air pipe. Paper Wasps like building in these and their nests are fairly small, open affairs, though I've seen them build as large as about 5 inches. If the nest was in the hot exhaust pipe, it's burnt away and your problems are over. If it's in the outer ring for the air insulation and intake, what was against the hot air exhaust is burnt, but the rest of the nest might be there in the cooler parts and the wasps alive and kicking. I'd be careful with the wasp spray, don't use it while the heating is running, but if the cap will come off, check to see if anything's visible in either of the vent portions, see if you can use a stick or piece of bent welding rod to snag it out.

Now if they were coming off from under the trim piece around the vent and they're Yellow Jackets, you might have a nest in the wall. That is a war of attrition as @Kenny kind of points out. They will overwinter till spring and it might take professional help to eliminate that. The usual method is to leave the holes open and spray till nothing living emerges. In winter time they hibernate so that plan kind of gets scuttled till spring. Once they're gone, then completely seal up all voids between the trim and the wall with silicone caulk.

  • What would happen in the spring if the hibernating yellow jackets were completely sealed in right now? Also, it appears to me that in very cold climates they hibernate elsewhere, so now is the time to seal openings for those in cold climates.
    – bcworkz
    Dec 8, 2012 at 19:12
  • Well, in my experience, they find a way out if there is one, worst case scenario into the attic where they find another exit and build a bigger nest. On newer homes that should be totally fire-blocked and insulated, there will be no other openings in the insulation bay that vent goes through for them to escape from (if this was planned in construction, there will be a fire block above and below that vent) and then they simply starve to death. And as things go, inside your relatively warm wall is an ideal place to hibernate. Dec 8, 2012 at 20:09

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