1) Mice can fit through a 1/4" hole. 2) There are myriad entry points into a car that mice can get through--for ventilation, drainage, and wiring. You're never going to close them all up. You can't close them all up; vents like the pressure relief flaps in the back can't be closed off by design. And, mice can chew (and must chew or their teeth will grow long enough that they can't eat). 3) This isn't a problem specific to the Prius or one that can be "designed out." 4) It's the luck of the draw. Most of us get lucky and don't have rodent intrusion. Just because there's a correlation with your specific preventative method doesn't mean it's a causal relationship. You probably just got lucky.
Years ago forgot about a bag of Winter Rye seed I left in our garage (used only for storage then) and the house got thoroughly infested that winter. Store bought poison bait worked like a charm, but there was that smell of dead mice for about 2 weeks after. Mice can get into just about anything so the only solution is kill them.
I have 13 bait stations outside my house and inside my garages I have more poison blocks. I live out in the country and am surrounded by farm and unused property. My wife found a dead mouse in the basement the other day and was really upset.
No, killing them leads to smelly futures. Just plug in some rodent repelents, ultrasonic devices that keep rodents away, the mice and rats live comfortably elsewhere and the humans haven't commited murder, nor do the carcas's emit ticks, fleas and noxic gasses.
That's what we put/have in the house. Bait poison was/is in the garage...not in the house. I do not put poison bait outside the house though. Problem was solved in a few weeks and has not returned years later. The smell dissipated quickly, no ticks, no fleas and FWIW I have no problem "murdering" mice and rats.
I think cats were mentioned, somewhat facetiously, as mousetraps. Seriously, are cats an effective way to deal with rodent infestations in cars? The only problem I can see is that after the rodents are gone, you still have the cat, so using a cat as a mousetrap would only really be practical if one was OK with the cat staying on as a pet. They are not disposable, like mechanical mousetraps. FWIW, we have cats, but they are only asked to purr and keep our laps warm.
After the cats perform their “mousetrap” duities, they assume their new role in the foodchain as dog food. Nature has already engineered this “green” approach.
Per the UltraSonic devices.. Most impartial sites have this to say: Expect Diminishing Returns: Pests such as rodents become accustomed to the sound from ultrasonic devices over time, so results may only be temporary. That, coupled with Baited Kill to remove the Mice Accustomed to the sound seems to be a nice balance. (IE, do Both).
It is commonly known that the CIA used dead animals as "dead drops" for materials and messages to agents in the field. To keep scavengers and other predators from eating them, they were doused with hot pepper sauce like Tabasco. Chemical deterrents work.
I had this problem about a month ago with packrats in my V in our driveway. I know they were coming from mor ethan 50ft away because I was finding pieces of plants under the hood from that far away. I am now squeezing it into our garage with my Prime. My past experience with a parked RV was that they get used to electronic repellants, and those pouches don't work. I've had mixed success with keeping lights on under the car (those decorative LED tubes that plug into a wall outlet and use less than 4W) I am opposed to poison because you also poison the natural predators (especially owls), who are trying to help you. WHAT HAS WORKED: scented dryer sheets. Just secure them under the hood in places where they won't be exposed to moving parts or very high temperatures.Change them every 2-3 months.
Just installed mesh in the aft of my 2011. It's stainless steel with only 1mm holes. https://www.amazon.com/gp/aw/d/B07QZRQHZS?psc=1&ref=ppx_pop_mob_b_asin_title Also installed over cabin air filter inlet under cowl. Will do the rest tomorrow after removing wiper motor assembly and metal cowl. But that's only part of the fix. Rat traps each night on top of front tire treads, peppermint oil sprayed in engine compartment several x per week, electronic deterrent under hood, rat trap with peanut butter on plastic sheet on top of passenger floor mat in case invader(s) still inside. No signs of rodents since.
Cats won't catch more than a few mice or rats if at all, but their presence will be sufficient to scare the mice and rats away and abandon the area. One caveat: If you don't have an indoor cat in your house, the outdoor mice and rats may decide to move in after they are scared by the outdoor cats.
I had a 71 Marquis that was getting infested with mice when it was stored. I made the mistake of putting a bunch of mouse poison inside of the car which caused them to crawl up into the headliner and die. The smell was ghastly. I ended up having to sell the big block 429 motor and scrap the rest of the car. At 9 miles to the gallon with high octane gas on the highway, that was no Prius...
I have had success with those glue traps. Just put a dab of peanut butter in the center and soon you will have mice stuck to it.
The easier method is to ply out the exhaust vents from under the car, fasten the screens to the verticals of the vents with nylon wire ties and snap them back in like I did in the attached pictures. I discussed it in this new thread; Easy rodent exclusion screen installation | PriusChat