I would wait until dark and they have settled down then plug the holes until they die. If they have established themselves you may need to remove the nest to free up your blower. Regardless, I would look for any flow obstructions, especially flammable ones, and remove them before trying to heat with the furnace.
I agree with getting the screens that are made for this purpose. When I first used the furnace in my camper, it would not run properly. I went outside and looked into the furnace exhaust/intake. There was a mud daubbers nest in there that I had to remove. After I put the screen on, I never had problems with anything in the exhaust again.
Bob & Dawn Married 34 years 2017 Viking 17RD 2011 Ford F150 3.5L Ecoboost 420 lb/ft Retired
I vote Carpenter Bees without seeing them. They are large and so similar in appearance to Bumble Bees most people cannot tell. Any exposed wood anywhere is a prime target. We had aboard on our porch/patio that was not treated. The holes from underneath weakened the piec to the point of breaking. they leave large about 5/8 or so in holes and deep that they then lay their eggs in. If you see sawdust piles behind the fridge, or places hard to get to even, carpenter Bees are probably what you have. Only the males sting I think. I set swatting them away while on the porch until I set out several Carpenter Bee Traps with holes at an upward angle, that draw them into a semblance of a small bird house, with a hole in the bottom. They can't find their way out and fly or fall down into a mason jar on the bottom. A hole is drilled in the lid and bottom of trap with lid screwed to the wood. Some people put a bit of water and soap in the jar or you can just leave it empty. Another version has the jar on the side, with a plastic fitting that lets them in but they can't figure out how to fly back out. Also a sticky colored several l sided card board trap with printings on it draws Carpenter Bees, Wasps, honey bees less frequently, and anything drawn to flowers and gheckos after the bugs. It has to hung way from the building or rv as with the other traps. If they are Bumble bees a pan of water near their nest is all that is required.Make it about 8inches or better across and about three inches or more deep and a drop of detergent. They fly over it and fall into it. I don't remember the why of it but it they just cannot fly over the water. Screens even though thee Lawyers of manufacturers say not to put anything over the inlets and outlets of furnaces and refrigerators are the only practical wy to keep them out, whatever they are. just don't let them clog up with lint, or any debris. Check them every time you head out or sit for a while, every time! You already have carpenter bees in the wood. Insert a long straw on can of insecticide or a pressure sprayer with some bug poison and make sure you get all the way to the larvae or eggs. I have had an angry mom fly out but dropped dead. They sell dorks of the right size to force into holes made by Carpenter Bees at Co-ops and Ace and other places or on the net.If you can get to them best to plug them as the hole is a magnet to the next generation of Carpenter Bees and other bugs. Then brush some wood preservative on the wood, all of it or spray it. They don't like Copper sulfate. It reminds you of army tents and supply rooms in smell. I woud spray any and all exposed to the outside wood under and round the coach and any and all openings.
This post reminds me of my friend. She stays in Greenwich, CT. She was also facing this same problem of bumble bees nest on the side of the house long back. Then at that time, she searched on the internet for some professionals in her area. Then she got to know about professionals from Pest Control Greenwich CT. She contacted them and exterminated her house. Likewise, you can also look for professional decent pest control company in your area by searching them on the internet.
As far as we love such pest, but we should also take into consideration the harm they may give. I remember my sister was also one of the biggest lovers of collecting green bee in her garden area, and the same reason they sought to attract other pets like critters and rats for making bees as their food. To get rid of these other pests attracted to her garden area, she took some helpful hints from Some pest controller like pest control in NYC etc. You should also take some helpful steps so that other pest may not harm your garden.
West coast bumblebees nest in walls, vertical surfaces. Not in the ground, that I have seen. Wasps sometimes nest in the ground.
OP, how sure are you thst you have bumblebees? If so, please be careful not to kill them, especially the queen. She will be huge and gentle, even less agressive than her minions.
3/4 timing in a DIY van conversion. Backroads, mountains, boondocking, sometimes big cities for a change of pace.
Use the screens referenced above that are made for the job as they HAVE to be metal or they will burn/melt on the exhaust port. Bumble bees nest in the ground so I think you have wasps. Honey bees need a larger space so probably not them either. If wasps and they have built a nest inside, you will need to remove it after killing the wasps as the nest will restrict airflow and the heater will not work due to overheating.
All the openings need screens. Nothing like opening the water heater access and staring at a 6" wasp nest. Amazing how fast an old fart can move. I wouldn't use fiberglass screen near any heat exhaust, use metal.
WD-40,, give the nest a shot,, won't kill all of em but they don't like the smell and wont come back!! Also Hot glue fiberglass screen material around the openings..
No mistaking a bumble bee since it's about the size of your thumb. Bees, wasp and yellow jackets are small, about as big around as a pencil. A bumble bee's sting feels like you've been his with a ball ping hammer, or at least that's how they feel when stung in the face/head.
The guards referenced above work against any of them.
If it's wasps floating around, grab a paper lunch sack, crinkle the top and hang it in that area. They will think it's a hornets nest and leave. Weird, I know...but it works.
