First try: peppermint oil in a water spray. Cleaned up the underhood area, sprayed the stuff all over, under engine cover etc. Smelled nice enough. Little b******s were back the next day. Not strong enough and doesn’t hang around.
Next try: Crank up the smells Figured something commercial strength might help: https://www.amazon.com/gp/product/B09CDYBMR2. Lazy cat is like strong pepermint and cinnamon spray. Not content to just let that ride I mixed in a bit of spice: https://www.amazon.com/gp/product/B07772GGD2/ too, pure capsicium or something. Spraying it over the engine compartment made me cry and I had to grab a mask to keep from burning my lungs. That’ll teach those f*****s!! NOPE. Plus the stuff burns off hot parts and car smells strange after driving the first few times, burnt mint and cinnamon. The mice don’t mind it all though. I would pray for any mechanic who would work on the car and rub an eye…
Get Serious: Trap ’em Clearly another approach needed. I read that keeping mice away is easier than evicting a current tenant, they like to come back home. So we gotta get rid of ’em. I already had this trap, proven to work in the house https://www.amazon.com/gp/product/B08DCYHSZN. It fit under the hood. Over the next 2 weeks, I put it under hood every night and take it out in the morning. Electrocuted 6 or 7 mice. And they still leave detritous around before they find the trap and venture in to their doom. So it kinda works, but also a pain. I trapped enough mice to destroy the theory it was just a comfy squatter, there were new tenants arriving nightly.
Desparation I was ready to try anything so naturally some cheap dollar speakers with flashing LEDs are fair game. I got 2 of these, https://www.amazon.com/dp/B07D118ZRJ the same ones I think referenced and pictured earlier in this thread, reviews and price seemed right on Amazon. Everything “works!” and “doesn’t work!” with this stuff. It’s proven consumer grade “ultrasound” doesn’t bother mice. And flashy lights, maybe a bit but not particularly effective. But hey, turns out they don’t mind peppermint and spicy stuff that makes your eyes water either. I got the 2 since they were cheap and I wanted to give the solution a real chance.
It’s been a week now, no rodent detritous, where it was crap and junk under the hood, every. single. day…
So I guess the Mouse Disco Party works. In this case at least. I can only theorize, but maybe the confined space and the random nature of the little flasher things is enough to freak out the prospective tenants. The speakers make a faint “clicky” sound too so that could be something too. It’s doing the trick so far for me.