Why Every Familiar Solution Fails At The Same Point
Walk through them honestly. Each one fails for the same structural reason, and it isn't the reason you'd guess.
Snap traps. They work. They kill the mouse you caught. They do nothing about the quarter-inch gap behind the dishwasher pipe that the mouse walked through, which is still there tonight. You are removing occupants from a building with an open door.
Poison. Same problem, worse consequences. The rodent takes the bait, retreats to its nest, and dies where you can't reach it which is why the smell arrives about a week after you thought you'd won. And the regulatory ground is moving underneath this whole category: California has banned first- and second-generation anticoagulants, with penalties up to $25,000 a day, and Washington is considering a moratorium that would sweep in bromethalin too.
Glue traps. The CDC advises against them, because a live, panicking, trapped rodent is something you then have to handle at close range. They catch birds and pets. New York City has a bill to ban their sale outright, and three California cities already have. And they still don't touch the entry point.
Ultrasonic plug-ins. The research record here is close to one-sided: a startle response, habituation within days, then nothing. Consumer Reports advises avoiding them. The New York Attorney General sent cease-and-desist letters to two manufacturers back in 2016, and the FTC has been warning about unsupported claims in this category for decades. Sound also doesn't travel through walls which is precisely where the mice are.
Peppermint oil on cotton balls. A mouse may avoid a treated spot at close range. Then the oil evaporates, roughly inside two days, and the spot stops being treated. More to the point: a mouse that has already found somewhere warm, dry and safe will tolerate a smell rather than leave. Once they're residents, scent doesn't evict them. Nobody selling you a bottle wants to say that out loud.
Quarterly professional service. A better applicator running a better formula against the same structural problem. Get three quotes in your area and do the arithmetic over ten years. Then ask the technician one question what happens if I stop paying you? and listen to the answer, because the honest ones will tell you: the mice come back.
Every single one of these treats the occupant. None of them changes the vacancy.