If you have mice living in your attic it is likely that they are traveling down through your wall voids to access areas of your home that have food or water sources.
Catch mice attic.
The trap must be big enough to catch the mice or they will escape.
Bait a humane rodent trap available online and at most home depot stores with cheese or peanut butter and set it in your attic.
Gnaw marks can be found on just about every hard surface such as your floor rafters in the ceiling house siding electrical wires ventilation ducts and areas around pipes inside your walls.
Check the trap daily and relocate the mice you catch several miles away from your house.
Snap traps and electronic house mouse traps are commonly used for killing mice.
One way exclusion funnels are also useful in removing mice from your attic.
You may notice recent gnaw markings as well as fresh mouse droppings around your house and attic space.
Lethal traps on the other hand catch and kill the mice instantly.
This is mostly done in a painless and quick way.