I've found no one thing works all the time.
Out of nowhere mice invaded my land, dug in, ruined "a lot of stuff," pooped and peed "everywhere," and really, really
cheezed me off. When their numbers kept increasing and there was no end in sight I finally decided this is a war and declared them the enemy.
War is hell, and this was going to be an ongoing conflict, costly, and time consuming. I'd taken losses on my side, it was time they took heavy casualties on theirs. I decided to hit fast, hit hard, see what worked, and then ramp things up.
I went on a recon mission and found Decon was stockpiled by the mice and not always effective, somehow some mice built up a resistance, and it was the same with bait pellets.
I dropped a fair bundle at the farm supply store on live traps, solid bait block stations, and bait. These worked, and worked well. The live traps caught 5 to 7 nice at a time and kept bait prices down. Solid bait blocks stopped the stockpiling of food, but again they built up a resistance to the poison.
I set up an account at
Solutions Pest and Lawn and bought higher quality products and at lower prices than the local farm supply store.
I found live traps with a bit of crushed bait block inside near the vent holes catches a fair amount of mice, especially when a block of wood is placed on the trap so it's more work for mice to jump over the trap instead of going into the hole. This is the cheapest, most effective trap in my arsenal.
Peanut butter scented sticky traps work great in the center of the building and along some edges, catching the "runners" that are hard to catch. (Some sill find a way to escape.) They're a bit costly, but do the job other traps don't.
Snap traps tied with string and baited with peanut butter catch mice that don't like to go into live traps and chew on the non-sticky edges of sticky traps. They're cheap and effective, the ones I use have a "cup" for peanut better (and holes in the trip paddle for peanut butter) so the mouse is likely to force the trap to trip. Tilt them nose-down to set, and nose-up to lock, super easy. Make a loop in the string and pass the trap through so a mouse can't make off with the trap--sometimes they do that).
I'm now also using outdoor bait stations with quite deadly soft bait. These are keyed and weighted down because other animals will try to get into them because of the scent. Mice love the soft bait and cleaned me out, so I've re-loaded with soft bait spread over peanut butter bait blocks so they have their choice of food and hopefully spend time eating the cheaper bait blocks, I'll know more over the holiday. This should drastically cut down on their ability to source reinforcements.
Sonic mouse repellers have done nothing no matter how many were used. Peppermint oil concentrate "kind of" works for 2-3 days then needs reapplication--due to cost it's best for negating mouse urin smell rather than repelling mice. A 5-gallon bucket, stick, and sunflower seeds has caught a couple mice, but unlike 50 years ago today's mice seem to learn quickly from watching their friends, and some are just really, really cautious, which is why I therefore don't buy any fancy traps seen on YouTube--no matter how many years YouTubers spent building "the best mousetrap" some mice will avoid it, others will learn from them, and the mouse invasion continues.
The indoor anti-mouse methods have wiped out indoor infestations. The outdoor bait stations haven't yet stopped all mice from wandering inside, but they were cleaned out so at some point the population of squeakers should markedly decrease.
The next step is to bend aluminum and seal the entryways. Unless they get boring equipment or hire rats to tunnel through it the ground invaders will be halted, though "attic mice" could still be a problem.
(I have no relationship with them other than as a customer and get nothing from this other than the satisfaction of perhaps helping a fellow forum member.)