Does citronella actually work to keep mice out or is it just a myth?

Essential oils like citronella or peppermint are mostly a waste of money when you have an active infestation. They might make the garage smell nice, but a hungry rodent isn't going to be stopped by a scent. It's mostly an internet myth that these provide any real protection. Mice are incredibly adaptable, and once they realize the smell isn't a physical threat, they'll walk right past those cotton balls to get to your insulation or workbench. If your neighbor's cat can fit through the gap at the bottom of your garage door, you don't really have a gap; you have an open entrance. A cat needs a couple of inches of clearance at minimum. A mouse only needs about a quarter of an inch—basically the diameter of a pencil. You're fighting a losing battle with pouches and oils until that **door sweep** is installed and sitting perfectly flush with the threshold. Even then, check the side seals because the vinyl weatherstripping often rots out at the bottom corners, leaving a perfect mouse-sized door.

Expanding foam alone is usually a waste of time because mice chew right through it like it's cotton candy. If you're sealing holes, you need to pack them tight with **stainless steel wool** or copper mesh and then foam over that. The metal mesh is what acutally stops them because it's abrasive on thier teeth. But if the main door is basically standing open for a cat, they aren't even bothering with the small holes you've already plugged. Since you can't use poison because of the cat, look into enclosed snap traps. You can make your own by cutting a mouse-sized hole in a heavy-duty plastic container and placing a standard snap trap inside. This keeps the cat’s paws away from the trigger but lets the mice in. Use peanut butter mixed with a little bit of cotton thread as bait. They have to tug on the thread to get the food, which almost always guarantees the trap fires. Citronella isn't going to save your garage. Focus all your energy on that door sweep and physical barriers. Once the garage is actually sealed, the mice already inside will be alot easier to catch because you won't have new ones coming in from the yard every night to replace them.

I'm curious about the door sweep too. I just bought a standard rubber one, but if they're chewing through foam, is rubber even enugh? I saw some sweeps online that apparantly have metal fibers built right into the gasket. Are those overkill for a detached garage, or is that the only way to actualy keep them out? I'd hate to install this basic one just to have them gnaw a hole through it the first night.

The metal fiber sweeps are definitely worth the extra cash. Look for the Xcluder brand—it’s basicly a rubber gasket filled with coarse stainless steel wool that they can’t chew trough. Regular rubber or vinyl is like a snack to them if they’re determined.

Also, check your vertical tracks. I’ve acutally seen mice climb those tracks like a ladder and squeeze through the gaps at the top header or where the track brackets meet the wall. Even with a perfect bottom sweep, you need to make sure the side weatherstripping is tight all the way up, not just at the floor level.