Getting rid of mice takes more than setting a trap and hoping for the best. If you only catch the mice already inside without sealing the entry points, new ones move in within days. The approach that works follows three steps in a specific order — Seal, Trap, Clean: seal every entry point first, trap and remove the mice already inside, then clean and disinfect contaminated areas. Skipping or reordering any step is why most DIY attempts fail.
Key facts:
Before doing anything else, confirm what you're dealing with. Mice leave specific signs:
Fresh droppings are dark and moist. Old ones are dry and crumble. If you're seeing fresh droppings in multiple rooms, the infestation is already established and you need to move quickly.
This is the step most people skip, and it's why their mouse problem keeps coming back.
Mice can squeeze through a gap the size of a dime. Common entry points include:
Use fill fabric or steel wool packed into gaps first, then seal over the top with spray foam or caulk — mice chew through foam alone. For larger gaps, hardware cloth or sheet metal is more reliable.
Seal before you trap. If you trap while entry points are open, you're playing a game you can't win.
Trapping is the most reliable way to eliminate mice already inside. Poison is slower, harder to control, and creates secondary problems — more on that below.
Remove what's attracting them first:
Where to place traps: Mice travel along walls, not across open floors. Set traps perpendicular to the wall with the trigger end facing the baseboard. Behind the stove, under the sink, inside cabinets near food, and along any wall where you've seen droppings or grease marks.
How many traps: More than you think. For an average kitchen, six to eight traps is a starting point. Mice are cautious of new objects in their environment, so covering multiple locations increases the chance one gets triggered.
Trap types:
Bait: Peanut butter is the standard for good reason — high fat, strong smell, doesn't dry out. Use a pea-sized amount. Too much and a mouse can steal it without triggering the trap.
Check traps daily. Reset immediately after a catch. Catching one mouse doesn't mean the problem is solved.
Mouse droppings and urine can carry disease — Hantavirus in particular is a real concern in the western US, including Colorado. The CDC recommends a specific protocol that should be followed carefully:3
If droppings are extensive, the area is enclosed, or there's contaminated insulation involved, professional cleanup is the safer call.
Safe cleanup steps in detail →
Poison creates more problems than it solves in most residential situations. It doesn't address entry points, so new mice keep coming. Mice often die inside walls, creating an odor problem that can last weeks. And if a pet or predator eats a poisoned mouse, you have a secondary poisoning risk.
Ultrasonic repellers are not supported by evidence. The Federal Trade Commission has warned companies making unverified efficacy claims for these devices.4 Mice habituate to consistent noise quickly.
One trap is almost never enough.
Some situations are beyond what traps and caulk can solve on their own:
A pest control professional can locate nesting sites you can't see, identify structural entry points, and set up a monitoring plan so you know when the problem is actually resolved rather than temporarily suppressed.
Connect with a local pest control professional →