The short version
Around Billings, Montana, rodent control means sealing mice out before fall, trapping rather than poisoning indoors, and treating every droppings cleanup as a possible hantavirus exposure. Montana has recorded 49 hantavirus cases and 11 deaths since 1993, mostly tied to deer mice in closed sheds and cabins.
- Montana DPHHS counts 49 hantavirus cases and 11 deaths since 1993.
- Deer mice carry the virus statewide; white-footed mice add risk in eastern Montana.
- Winter lows near 15F drive mice into Billings garages every fall.
- Spring cleanouts of closed sheds and campers carry the most risk.
Use this if you live in Billings and found droppings in the garage, heard mice in a wall, or are about to clear out a shed, camper or cabin after winter.
What to look for
Both are native field mice that slip into buildings nobody uses. With only about 14 inches of rain a year, droppings in a closed shed dry fast and crumble into dust when disturbed, and that dust is how people breathe in the virus. Four rodents matter here: the deer mouse, the white-footed mouse, the house mouse and the Norway rat. Montana DPHHS names the deer mouse as the hantavirus carrier statewide, with the white-footed mouse adding risk in the east.
- 1Tiny dark droppings across a camper mattress after winter storage.
- 2Shredded cardboard or insulation nests in garage boxes.
- 3Seed husks piled in a hidden corner, since deer mice stockpile food.
- 4Rustling in walls on cold nights starting around October.
- 5A stale, musty smell when you open a closed building.
Why it’s worth acting soon
- Every month a shed stays infested adds droppings someone must clean.
- Fall arrivals keep breeding through winter inside heated walls.
- Chewed wiring in garages and campers can mean a fire hazard.
- A rushed spring cleanout with a broom is the classic exposure.
49 cases, 11 deathsHantavirus cases in Montana since 1993Montana DPHHS Treatment options and typical costs
Exclusion and sealing
Quoted after inspection
The provider closes gaps at the foundation, garage doors, vents and pipe entries with steel wool, hardware cloth, sheet metal or cement.
- Time
- Set after the exterior inspection
- Best for
- Houses and attached garages
Snap traps placed and checked
Quoted after inspection
Traps line walls and storage areas and get checked on a schedule until catches stop, so no mouse decays behind drywall.
- Time
- Until catches stop
- Best for
- Mice already indoors
Outbuilding cleanout
Quoted after inspection
For a shed, camper or cabin with heavy nesting, some companies clean up using respirators, disinfectant and sealed bags. Ask whether soiled insulation gets removed.
- Time
- Depends on how much nesting there is
- Best for
- Spring openings
Prices are typical published ranges. Ask what’s included before you compare quotes.
Roof rats and mice love attic insulation. Tunnels through the fluff, flattened runways and droppings along the eaves are the signs to look for.Why does Montana take hantavirus so seriously?
For Billings households with a garage or camper, that is the risk to plan around. What they share is an activity, usually cleaning a building full of deer mouse droppings. The median age is 45, with cases from 8 to 68. The patients are not who you might expect. From 2020 through 2025 there were 6 cases: 2 became the severe lung illness and 4 were milder. Montana DPHHS has recorded 49 hantavirus cases since 1993, and 11 of those people died, a heavy burden for the state's population.
Before you open the shed: a spring cleanout plan for Billings.
With 14 inches of yearly rain, droppings dry quickly and a broom turns them into the fine dust that carries the virus. Wipe up with paper towels, double-bag everything, and mop shelves with the same mix. Put on rubber gloves, mix 1.5 cups of bleach into a gallon of water, and soak every pile, nest and stain for 5 minutes. Open doors and windows and walk away for 30 minutes. Spring is when Billings residents uncover winter damage and when hantavirus risk peaks across Montana.
This is what a proper seal looks like: metal mesh fastened with screws and sealed at the edges. Foam or caulk on its own gets chewed through.Deer mouse or house mouse: how to tell them apart.
Deer mice are sharply two-toned, brown on top and bright white underneath, with a tail that is also dark above and white below. White-footed mice look nearly identical. House mice are a dusty gray-brown all over with a scaly, nearly hairless tail. Behavior helps too. Deer mice favor sheds, campers and unused buildings and stash seeds in boots and drawers, while house mice settle near your food. If you are not sure, assume deer mouse, since the cleanup precautions cost almost nothing.
Sealing is the part that lasts in Billings.
Around Billings, MT, 14 inches of rain a year and 56% humidity keep exterior wood soft, so gaps open again seasonally and need re-checking. A mouse fits through a gap the width of a pencil, and a rat through a quarter-sized hole, so the inspection should map every opening — around pipes, under doors, and where utilities enter. Traps and bait remove the rodents you have; sealing removes the ones that would come in next.
What rodent control costs in Billings.
Ask for the sealing and the trapping as separate line items, and what the re-service covers. Around Billings, MT, the timing matters too — most activity starts in fall as 15°F winter lows push rodents indoors, which is when providers are busiest. A simple kitchen mouse job is at the low end; a multi-floor rat colony with a sanitation cleanup is at the high end. Rodent control is priced by the size of the job: how many entry points need sealing, how much baiting and trapping the colony needs, and whether a cleanup is involved.
What affects the price
- The number of sheds and detached garages needing inspection.
- How much nesting must come out before sealing starts.
- Whether contaminated insulation or stored gear is included.
- How many openings turn up around siding, vents and doors.
- Rats versus mice, since rat work adds outdoor stations.
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What's your biggest concern about rodents?
When to call for help
Bring in a provider when activity is in a building you rarely use or the droppings are heavy enough that cleaning feels like a project. Montana DPHHS reports patients are usually exposed cleaning cabins, sheds and outbuildings, and their median age is 45, with cases from 8 to 68. Call too if traps keep filling after two weeks.
What you can do yourself
Plenty of Billings homeowners handle a few mice alone. A row of snap traps along garage and basement walls can clear a small population, and a rubber sweep on the garage door closes a common gap. The hard part is finding every 1/4-inch opening along the sill plate, and the dirty part is a camper that hosted mice all winter.
Rodents in Billings
Summers near 88F and lows near 15F make the fall move indoors sharp. As the largest city in Montana, with about 119,000 residents and the Rimrocks for a backdrop, it has no shortage of garages, sheds and campers to shelter rodents. Dry air pushes mice toward indoor water near sinks, water heaters and pet bowls. Billings sits at 3,124 feet on Montana's semi-arid plains, with average humidity around 56 percent. In Billings, comparing a couple of written quotes side by side is the easiest way to see what is actually included, because the scope, prep steps, and follow-up terms vary a lot between providers. Most providers include a follow-up visit in the plan, but the terms differ, so ask exactly what is covered and for how long before you decide.
Local research
Rodents in Billings, MT: what the public record shows
Before you compare quotes, it helps to know which rodents actually live in Montana, when they are busiest around Billings, and what the state figures look like. Everything below links to the agency or university page it came from.
Rodent species recorded in Montana
- House mouse (Mus musculus) — Enters at 1/4 inch; 5-10 litters per year; eats about 200 small meals a night.
- Norway rat (Rattus norvegicus) — Burrowing rat of basements, sewers and ground floors; tail shorter than head plus body.
- Deer mouse (Peromyscus maniculatus) — Primary U.S. hantavirus carrier; lives throughout Washington and the interior West.
When rodents are busiest around Billings
Risk peaks when closed-up cabins, sheds and outbuildings are opened and cleaned in spring.
Montana DPHHS follows CDC's seal up, trap up, clean up sequence: never sweep or vacuum droppings.
For context, nationally
- 1/4 inch (the width of a pencil) — Smallest gap a mouse can enter. CDC
- 890; 35% fatal; 94% west of the Mississippi — Hantavirus cases reported since 1993 (through 2023). CDC
Sources: Montana Department of Public Health and Human Services, Communicable Disease Epidemiology; CDC; Pest Notes: House Mouse; Pest Notes: Rats; Hantavirus. Figures are quoted as the source prints them. How we check our sources
Simple ways to keep rodents away
- Seal gaps around pipes and vents by September, before nights freeze.
- Fit a tight rubber sweep on the garage door.
- Store birdseed and dog food in metal bins, not paper sacks.
- Let a closed shed or camper air for half an hour before cleaning.
- Pack cabin bedding and camping gear in sealed tubs over winter.
- Cut tall grass back from the foundation, where deer mice travel.
In a multi-unit building, mice move between apartments through shared walls and pipe chases, so treating one unit rarely solves it. Ask for a building-wide plan.Did you know?
Of 6 Montana hantavirus cases from 2020 through 2025, 4 never became the severe lung disease.
About 94 percent of US hantavirus cases from 1993 through 2023 came from west of the Mississippi.
The US averages about 7 human plague cases a year, spread mainly by rodent fleas.
Questions people ask
How common is hantavirus in Montana?
Uncommon, but Montana carries more than its share: DPHHS has recorded 49 cases and 11 deaths since 1993, with zero to two in a typical year. Most patients were exposed cleaning outbuildings, so Billings residents should treat spring cleanouts seriously.
Do house mice in Billings carry hantavirus?
House mice are not the carrier Montana officials point to; the deer mouse and white-footed mouse are. Droppings look alike, though, so treat any found in a Billings garage, shed or cabin as if they could carry the virus.
What is the safest way to clean a shed full of droppings?
Air it out, wet it down, then wipe and bag. The CDC says to ventilate for 30 minutes, spray droppings with 1.5 cups of bleach per gallon of water, wait 5 minutes, then pick up with paper towels.
When do mice move indoors in Billings?
Expect the push from late September through November, as lows slide toward the 15F average. Mice spend hot, dry Billings summers in fields and yards, which makes June through August the best window for sealing.
Should I use poison or traps for mice?
Indoors, snap traps are usually the better pick. A poisoned mouse can die inside a wall, leaving odor and a contaminated spot, while traps show results and are easier to keep away from kids and dogs.
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Sources (6)
The facts in this article come from the public sources listed above. Every home is different, so ask the company you talk to about pricing and what’s included. Published by Rodent Exterminator · Updated October 11, 2026 · How we write these guides