Rodents in ceiling

[scott2020]

Hi all. I'm hoping someone can lead me in the right direction. We had a few mice in the Fleetwood over the winter as it sat outside unused. I do place traps and catch some here and there. Yesterday we got her out and started cleaning things up and I found a bunch of insulation that had fallen out of one of the AC ducts. Something has been crawling around in the ceiling. I also found a bunch of what looks like acorns, mostly around the master bedroom slide area. I'm wondering if things are getting in there.

Are these mice, or maybe chipmunks? How are they getting in the ceiling?

I took apart both AC units and I can't see a way they could get in from the top, but who knows.

Appreciate any advice!

Sorry I can't rotate the pics correctly...

[MrMark52]

To get pictures to rotate correctly, do a quick edit of the picture (I usually do a minor crop), and save. Then post the edited picture.

I’m inclined to think your varmints might be squirrels or rats - but regardless of what they are - finding their path of entry can be difficult.

You would be surprised how easily rats can climb. I’ve seen them climb exposed wooden studs inside of a garage to reach and crawl into an attic. Am thinking mice can do the same (rats/mice easily crawl up the tires of a MoHo to get to the wiring or get into the coach anyway).

[jacwjames]

I lived in our coach while I was building our new house, which is located on a heavily wooded lot. I had problems with mice and probably squirrels. I set traps and also up some of the small pouches of mouse repellent (smells like wintergreen) up in the ceiling which seemed to help. That was in 2018.


Fast forward to 2021. I was on a trip and all of a sudden the generator would die when I turned on the inverter, had to head home fix. I ultimately narrowed the problem down a 120 volt wiring circuit coming off inverter. It was in the ceiling, I had to bypass that section but was able to get the entire circuit back running.

I had a problem with the rear AC ( not mouse related), 20 years old so decided to change both AC's. While I was into it I decided to inspect my AC ducting in the ceiling using a remote camera. I found evidence of mice, at the front and back they put holes in the duct, plus a large hole towards the center which was right next to a light fixture.

I was able to fix all three of these holes but the biggest problem was a manufacturing defect. When the installed the ducting in the ceiling at the factory they did not do a good job of mating two pieces together and did not use any tape, I had a ~1/2" gap on 3 sides of the duct. To fix I had to cut a hole and add another duct register, which was OK and turned out good.



Unfortunately you are probably only seeing some of the potential problems.



Last year 2022 I was adding a fuel pressure gauge to my rig and when I dropped the ceiling I found a huge mouse nest (mansion). I also found several large snake skins, not sure which was worse, but at least snakes don't chew wires.

To alleviate my problem to some extent I built a 40X50' garage to park my rig in, have not seen any other evidence since in the motor home.

Just fixed a wiring harness on my Jeep that appears to be mouse/rat chewing and last year a wire on my suburban was chewed.

[scott2020]

Thanks for the replies! I live in Missouri and have this parked next to a wooded area. I want to build a garage, but I might put it in storage over the winter. I'm afraid to see what is above the ceiling. With that much insulation moved around I bet there is some big nest up there. I haven't seen any rats around here but plenty of mice, tons of chipmunks, and so many squirrels you can't count them. Maybe I can get a camera to go up there and try to see what is going on, not that I could do too much about it.

[jacwjames]

Besides the normal points of entry I ultimately found a large hole back by the engine, passenger side where my air intake grill/box is. They had used a bunch of spry foam to seal everything up and I found a huge hole there.

After that I did spend time going around with cans of spray foam sealing up holes. You can also use some of the dish scrubbing coiled wire and shove around pipes, they don't like chewing through that.

But the biggest openings are at the front and back, between the chassis rails where they ran all the electrical and plumbing. The back was pretty easy to get to but the front is not accessible due to the fuel tank without taking down ceiling panels in basement. Lots of openings there and pretty easy access for a varmint of any size (and probably snakes).

[Argosy]

Originally Posted by jacwjames

Last year 2022 I was adding a fuel pressure gauge to my rig and when I dropped the ceiling I found a huge mouse nest (mansion). I also found several large snake skins, not sure which was worse, but at least snakes don't chew wires.

You had snakes because of the mice, they feast on them.

[jacwjames]

Originally Posted by Argosy

You had snakes because of the mice, they feast on them.

Yup, I actually left one snake skin where it was for a while knowing that the mice would smell it and stay out.



Don't mind snakes from a distance, but they have been known to sneak up on me and make me have an accident in my pants

[astrnmrtom]

Without seeing the critter, your best bet to identify them is to find some droppings. Then go online and search for pictures to identify the pooper by their poop.

You'll want to find where they are entering and seal it up ASAP. Don't want them setting up house and breeding.

You can use a flashlight and a mirror to check your ducts.

Don't vacuum up droppings or sweep dry. Always clean using a mild bleach solution or disinfectant. Pre-wet the waste and give it a short dwell time before wiping. Deer mice and rats are carriers of the Hantavirus and Leptospirosis, and they secrete it in their feces and urine. You can inhale the dry waste dust which contains the virus or bacteria.

If you have a large population of squirrels, that would concern me. In the pest control world that's called high pest pressure. High pest pressure means lots of competition for resources. Squirrels usually chew fairly large holes. Mice can fit through an opening the size of their skull, so if the end of your pinky finger fits, so can a mouse.

I'd set some traps too and see what you catch. Mice are pretty easy, with rats you need to pre-bait an unset trap. Rats are warry of new things, are smart, and may test the trap, and if it snaps, they'll avoid it from then on. Let them get used to taking some bait off the trap before setting it. For rats you'll need larger traps and for squirrels a specific trap to catch them. Oh, and rat traps should be secured to something with a piece of light chain or a wire. You don't want a wounded rats dragging a trap off into an unreachable place.

Happy hunting.

[scott2020]

Thanks for the tips! I have been catching some, I think 4 so far. I also mixed up a 1:10 bleach/water solution for hard surfaces and I'm using household disinfectant on soft surfaces to sterilize as best I can, picking up with gloves/paper towels, etc. I found some mouse droppings on the floor, carpet, and in the AC ducts with the styrofoam scattered around in the ducts.

The far rear duct is the first picture in the first post. That is where almost all of the insulation material had dropped down through the duct. I took all that down and found a tunnel through the ceiling heading toward the rear. I put some steel wool in the tunnel and filled with spray foam. Maybe they are tunneling up the wall and across the ceiling? It's pretty hard to see viewing from the basement up. I do see plenty of droppings in the basement areas and around the storage tanks, water pipes, all of that. I'm thinking they climb up the tires maybe, get in the basement, and go to down from there.

My worst fear is a nest somewhere in the ceiling or wall, and after it warms up a bunch of who knows what will start scurrying through the RV! GROSS.

Other than the acorns, I don't see anything that would indicate something other than a regular mouse. Maybe mice carry acorns around, I don't know! There are acorns inside and several throughout the basement.

yuck!

[Coarsegold]

Hope your damage is small but mice can get into anything.

You may not have seen my previous thread on how most RV insurance companies do NOT cover mice, rodent, or any animal damage. I urge everyone to read their insurance policy under such titles as not covered, exclusion, or excluded.

Repairs can get into the thousands of dollars when they move past insulation chewing into wiring in the coach or engine compartment. Geico just told my daughter NO coverage on her recent RV mouse issue.

[scott2020]

Originally Posted by Coarsegold

You may not have seen my previous thread on how most RV insurance companies do NOT cover mice, rodent, or any animal damage.

I might have missed that, but I believe it when someone says the insurance company will find ways to NOT pay for something. So far I haven't found major damage, and everything is working like I expect it to. I am going to keep some traps set and see what they get. I also will be setting a trap for chipmunks. My neighbor's cat comes around every night on his prowl so maybe things could be worse!

I just wish I could pinpoint where they got into the ceiling.

[astrnmrtom]

The most important thing you can do to stop this, is find where they are entering the rig.

Here's some tricks I learned from my years as an institutional pest control guy. Follow they tips and use the methods below to earn your Jr. Past control badge. ;^)

1. Look for debris, chew marks, and droppings. Obviously you know this one.

2. When checking the rig inside and underneath, a place where they are going in and out will be brushed clean of dust from their fir. If used long enough, oil from their fir will make the opening look greasy.

3. Clean up the droppings as best you can, then inspect regularly, noting where you first see dropping appear again. This can be a clue that an entry point is close by.

4. Don't just look with your eyes, probe with your fingers. Pay special attention to bundles of wires or hoses. They may look well foamed from the factory but can have gaps in the center that mice can use.

5. Mice CAN jump, and climb a surprising variety of surfaces.

6. Never underestimate your opponent. They have tiny brains but are experts in survival, and they are on duty 24/7/365. You are battling pros. I can't overstate this enough.

7. I spent 16 years fighting them professionally, and to this day they'll still occasionally get the best of me. See #6. I do mouse inspections every time I service my rig to check for new entry points. I also keep two monitoring traps loaded, one inside near my pantry, and one underneath in the main storage compartment. In the past 3 years of full timing I've been mostly mouse free. I say mostly because twice, I've caught a mouse in the storage compartment trap. The first one was from a previously factory foamed hole that the foam broke loose out of, and the second, just recently was an entry point that I was SURE didn't penetrate into the rig. It was a drain hole for my hot water tank overflow in a sheet metal box right above my rear tire. turns out a couple of my hydronic hoses enter this box from the interior compartment and this can't be seen or felt from anywhere. The drain hole is now blocked with a stainless steel scrubby pad. Water can drain out, but mice can't enter. What clued me in that a mouse was inside were some chewed paper towels in the storage compartment, that just two days earlier, weren't chewed. Checked my trap and sure enough - got one. Grabbed my detective cap and flashlight and started looking for an entry spot.

I got lucky this time because I've become more lax on checking my traps, which bring me to advice #8. Never assume you've won. See #6 above. If you are sure you have it all sealed up, monitor it regularly with either traps or sticky boards.

So, here are the three steps the pros take:

1. EXCLUSION, it's in caps because it's the most important.
2. Bait outside the rig. This reduces local populations which in turn reduces pest pressure. (less effective when traveling unless you stay in a place for a while)
3. Monitor with traps or sticky boards. This will be your mouse alarm system. Check them regularly.

When my rig was in storage in an unsealed building surrounded by fields, I maintained two pet/child resistant bait stations loaded with BLOCK style bait. (Mice can run off with and hoard pelleted style bait) One near the front of the rig against the inside of the tire, and one beside the inside edge of the rear tire. If you are adverse to using bait, make yourself a couple bucket traps, and place a couple near the rig. I checked all my traps and refilled my bait station monthly when I visited to exercise the generator (also poked around inside with a flashlight). Check more frequently if you store your rig nearby, especially early on. If the bait does it's job, you should notice less and less of it being consumed over time.

I placed interior traps in several likely mouse places. I used reusable electronic zap traps (not repellant devices, they don't work) but snap traps or any baited trap will do. Be sure to place the traps properly. Baited end against a vertical surface if using a snap trap. Mice navigate by touch as well as smell (they leave urine trails) and placing the baited end against the wall puts the bait right where they'll run into it. For covered traps with openings, place them against the wall, so they approach the trap and encounter the opening.

That's rodent control 101. Pay attention to any clues you may see. If you put a few traps around inside they too can be a clue as to where an entry point "might" be, especially if you catch a mouse in that area, reset and catch another in the same trap.

When you inspect, be sure to check under the front and rear cap areas. Follow hoses and wiring harnesses and be sure the seal is good where they penetrate any wall or floor. Remember the pinky-tip rule.

I'll leave you, and others who've slogged through my long posting with a couple Rodent Fun Facts:

Rats have a 21- to 23-day gestation period.
have 5-10 rat pups per litter.
produce 3-6 litters in a lifetime.
live an average of one year.

Two rats can become over 1200 in a year!

The huge explosion in Rat populations can be partly attributed to a change in how we handle our trash. At one time trash cans were made of metal which is rat proof is the lid is on tight, but this has been replaced with the plastic trash bag, which when set out, is now easy pickins for rodents. More food means more Rats.

Rats have a natural fear of novelty, meaning they are cautious about changes in their environment. This allows them to quickly learn and avoid new hazards. Recent research has shown these fears can be passed down to offspring through epigenetic changes. The DNA itself doesn't mutate, but pieces of it are switched on and off. This means a smell that's learned as being related to a danger by the mother, can be seen as dangerous to the offspring even if they haven't encountered the danger themselves.

Rat birth control - the next step in Rat control? Experiments are being done with bait that contains ingredients that act as rat birth control pills. This approach is being seen as a safer alternative to poison. If rats live without being able to breed, populations will fall, with no danger to pets or children. So the next time you see a few million dollars being spent on researching rat reproduction, don't scoff, it may lead to a more effective and safe way of reducing their population.

That concludes today Rodent lesson. Now, go out there and FIGHT!

[scott2020]

Great information and advice! I am going to do everything I can to identify where they are coming in, and I have several more places to check. If there is a nest of babies getting ready to bust out and explore the world, I guess I'm in trouble and will have to deal with it. Such is life!