Mouse & Rat Control

Mice, rats and the seasons

Rodent calls rise every fall around Denver. As nights turn cold, mice move from fields, gardens and open space into garages, crawl spaces, basements and wall voids. House mice and deer mice are the two we see most. House mice are gray-brown with nearly bare tails. Deer mice have a sharp line between a brown back and a white belly, and a tail that is dark on top and pale underneath. We see rats less often than mice, but both Norway rats and roof rats occur in Colorado, and a rat problem needs a different plan from a mouse problem.

Deer mice and hantavirus

Deer mice can carry hantavirus, a rare but serious lung infection. People can catch it by breathing in tiny particles from the urine, droppings or nests of infected mice, especially in closed, poorly aired spaces such as sheds, cabins and garages. Colorado public health agencies advise airing out the space before cleaning, wearing rubber or latex gloves, spraying droppings and nests with a disinfectant or a bleach and water mix and letting it soak before wiping up with paper towels, and never sweeping or vacuuming droppings. If you are not comfortable doing that cleanup yourself, tell us, and we will talk through the options.

How we get rid of them

Indoors, we use snap traps placed along walls and in the runways rodents travel, because traps let us remove the rodents instead of leaving them to die inside the walls. We set them where children and pets cannot reach them, and we come back to check and reset them. Outdoors, we may place locked, tamper-resistant bait stations along the foundation, following the product label, but we do not use rodent poison inside the living space. Each visit, we note what was caught and where, which tells us where they are getting in.

Sealing them out

Trapping alone is a cycle. As long as there is a way in, new mice will find it. A mouse can squeeze through a gap about the size of a dime, and a rat through one the size of a quarter. We look for gaps around pipes and wires, under garage doors, at foundation vents, in the gaps where siding meets the foundation and around the air conditioner lines. We seal them with steel mesh, metal flashing and sealant, materials rodents cannot chew through.

What you can do

Keep pet food, bird seed and grass seed in sealed containers, bring trash and compost bins in at night, move wood piles away from the house and cut back dense shrubs along the foundation. In Denver, the city public health department inspects alleys and public property for rodents, and you can report rats on public land by calling 311.