The short version
Rodent control in Spokane Valley, Washington is mainly about house mice, deer mice, and Norway rats moving into garages, crawlspaces, and walls from September through November, then staying through winter lows near 23F. Seal every gap of 1/4 inch before fall, trap along walls, and clean deer mouse droppings wet, since infected deer mice live throughout Washington.
- Fall, September through November, is the main entry window in Spokane Valley.
- Mice that get in stay in walls and garages all winter as lows drop toward 23F.
- Infected deer mice live throughout Washington, so droppings need wet cleanup.
- Rats carry litters only about three weeks and breed by 3 to 4 months, per WDFW.
- Seal with durable materials, since rats chew small holes larger.
This is for Spokane Valley homeowners hearing scratching in the walls once the furnace comes on, families finding droppings in the garage or shed, renters wondering what their landlord should handle, and anyone about to clean out a closed storage space after winter.
What to look for
House mice are the most common indoor rodent here. They slip through openings around 1/4 inch and nest in wall voids, kitchen cabinets, and basement storage. Deer mice live outdoors in fields and brush and move into garages, sheds, and crawlspaces, carrying hantavirus. Norway rats burrow along foundations and garage slabs and work their way into crawlspaces. Spokane Valley's warm summer continental climate sets the pattern. Summers are warm, with highs near 84F, and rodents breed outdoors. When nights cool in September, they start pressing toward buildings, and the main entry window runs through November. After that, 23F winter lows give them every reason to stay put until spring. The area is fairly dry, with about 17 inches of precipitation a year and humidity near 64%, so irrigated yards, pet bowls, and dripping faucets draw rodents close to the house. At about 2,001 feet, fall can turn cold quickly, so sealing in August pays off.
- 1Droppings in the garage, under sinks, or along basement walls.
- 2Scratching in walls or ceilings once nights turn cold.
- 3Nests of shredded paper or insulation in garage storage.
- 4Burrows along the foundation or beside the garage slab.
- 5Chewed bags of bird seed, grass seed, or pet food.
- 6Small footprints, about 1/2 inch long for rats, in dust or mud.
- 7Gnawed wood, wiring, or plastic with fresh, pale marks.
Why it’s worth acting soon
- A mouse pair that slips in during October can fill a wall void by March.
- Rats have litters of 6 to 10 young after about three weeks of gestation, per WDFW.
- Chewed wiring in walls and garages creates fire risk.
- Deer mouse droppings in closed spaces raise hantavirus exposure during cleanup.
- Rats chew small holes larger, so a minor gap becomes a bigger one.
Treatment options and typical costs
Pre-winter exclusion
Quoted after inspection
Sealing every gap of 1/4 inch or more with hardware cloth, sheet metal, steel wool backed by sealant, or mortar, ideally in August or early September. Focus areas include garage door seals, utility entries, crawlspace vents, and foundation cracks. Ask for photos of each sealed point.
- Time
- Depends on how many gaps turn up
- Best for
- Homes with a repeat fall mouse problem
Snap trapping
Quoted after inspection
Snap traps placed along walls in garages, basements, and kitchens catch mice where they travel. Larger traps go along runways for Norway rats. A provider should check and reset traps until a full check shows no new activity.
- Time
- Until a full check shows no new activity
- Best for
- Active mice or rats indoors
Crawlspace work
Quoted after inspection
For Norway rats in crawlspaces, a provider may screen vents, seal foundation gaps, set traps along runways, and recommend cleanup of soiled insulation. Ask what is included and whether the crew uses respirators for cleanup.
- Time
- Depends on what the crawlspace needs
- Best for
- Homes with rats under the floor
Cleanup and disinfection
Quoted after inspection
For garages, sheds, and crawlspaces with deer mouse droppings, the CDC method calls for ventilating 30 minutes, soaking with bleach solution for 5 minutes, and wiping rather than sweeping. Ask how contaminated material is bagged and removed.
- Time
- Depends on how heavy the contamination is
- Best for
- Closed spaces used by deer mice
Prices are typical published ranges. Ask what’s included before you compare quotes.
Crawl spaces are where rats and mice get comfortable. Vent screens, the sill plate and any gap around pipes are worth a careful look.Which rodents does Spokane Valley actually deal with?
Across Spokane Valley, three of them do most of the damage. House mice are small and gray-brown. They live indoors once they get in, nesting in walls, cabinets, and storage, and they need only a gap of about 1/4 inch. Deer mice have brown backs, white bellies, and sharply two-toned tails. They live outdoors and move into garages, sheds, and crawlspaces. The Washington Department of Health says infected deer mice live throughout the state, so their droppings need careful cleanup. Norway rats are heavy, brown-gray burrowers. They dig along foundations and garage slabs and get into crawlspaces through vents and gaps. Roof rats are the fourth species, but the state notes them mainly in Puget Sound attics. Identifying which you have shapes the plan. Small droppings in drawers point to mice. Burrows and larger droppings point to rats. Washington's state data lists four rodents: the Norway rat, roof rat, deer mouse, and house mouse.
Fall into winter: Spokane Valley's rodent calendar.
From June through August, with highs near 84F, rodents breed outdoors. This is the best time to seal. Replace garage door seals, screen vents, and seal utility entries while nothing is trying to get in. September through November is the main entry window. At about 2,001 feet, nights cool quickly in fall, and mice and rats start testing garages, crawlspaces, and foundation gaps. Set traps along garage and basement walls early in September. From December through February, lows near 23F keep rodents inside. Mice continue to breed in walls and garages, so keep traps checked and look for new droppings each week. March through May is cleanout season. People open sheds and garages after winter, and deer mouse droppings mean hantavirus exposure risk. Use the CDC wet cleanup method. Following this cycle keeps the yearly work small and predictable. Spokane Valley's rodent year is driven by the cold, and timing your work to the calendar saves effort.
Dense shrubs against the house and a dripping hose bib give rodents cover and water. Trimming back and fixing drips makes the yard less inviting.Deer mice and hantavirus around Spokane Valley.
Statewide, that adds up to 1 to 5 cases in a typical year, and roughly a third of diagnosed patients have died. CDC provisional tables counted 1 Washington case in 2025. Deer mice live in fields, brush, and open ground, and they move into garages, sheds, crawlspaces, and stored items. With only about 17 inches of precipitation a year, irrigated yards and garages with stored food are attractive. The risk comes from dried droppings and urine in closed spaces. Sweeping or vacuuming puts particles in the air. The CDC method avoids that. Open doors and windows and ventilate for 30 minutes. Wear gloves. Spray droppings with a bleach solution of 1.5 cups per gallon of water, wait 5 minutes, and wipe with paper towels. Bag everything. For heavy contamination, hire a crew with respirators, then seal the space. The Washington Department of Health says infected deer mice live throughout the state, and Spokane Valley's drier climate does not change that.
Rats breed fast: what a three-week gestation means.
Those numbers explain why rat problems in Spokane Valley grow so fast if you wait. A pair of Norway rats that gets into a crawlspace in October could have a litter by November and another by December. By spring, the first litter is breeding too. A small problem in fall can be a large one by April. This is why timing matters. Sealing before fall prevents the first pair from getting in. Trapping as soon as you see signs catches them before the first litter. Waiting until spring means dealing with several generations. Rats also chew. WDFW notes they can start through a 1/4-inch hole and chew it larger. Weak repairs with foam or thin mesh often fail. Durable materials like hardware cloth, sheet metal, and mortar hold up. Ask any provider how they plan to handle follow-up through winter. WDFW reports that rats carry their young for only about three weeks, produce litters of 6 to 10, and the young begin breeding at 3 to 4 months.
What a provider should seal on a Spokane Valley house.
Garage doors are the first stop. Bottom seals wear out and corners open up. A provider should replace worn seals and close gaps at the sides. Utility entries come next. Gas lines, water lines, cable, and AC lines pass through walls, and the gaps around them are often unsealed. Steel wool backed by sealant, or sheet metal, closes them. Crawlspace and foundation vents should be screened with 1/4-inch hardware cloth. Foundation cracks need mortar or patching. Dryer vents and roof vents need covers that close properly. By the end of the visit, you should have a written list of every point sealed and the material used, along with a trap plan and follow-up schedule. Ask for photos. Rats chew small holes larger, so durable materials matter. A sealing job done in August holds best through the fall push. A good exclusion job on a Spokane Valley home focuses on the garage, the foundation, and the crawlspace, since that is where most rodents get in.
What affects the price
- Count of openings to close, plus how awkward each one is to get.
- Crawlspace access and whether insulation needs removal.
- Garage size and stored items to move.
- Whether Norway rats are involved, adding devices and visits.
- Sheds and outbuildings needing their own inspection.
- Follow-up visits through fall and winter.
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What's your biggest concern about rodents?
When to call for help
Bring in a provider when mice keep appearing after a couple of weeks of trapping, when you see burrows along the foundation, or when droppings show up in several rooms. Across Spokane Valley, calling in August or early September, before the fall push, gives a provider time to seal before rodents are inside for the winter. A pro also helps with crawlspaces, which are tight and dirty to inspect, and with any closed shed or garage that has heavy deer mouse droppings, since cleanup carries hantavirus risk.
What you can do yourself
DIY handles a good share of Spokane Valley mouse problems. A new garage door seal, steel wool and sealant around pipe entries, snap traps along walls, and seed and pet food in metal cans will clear a small, recent problem. The CDC cleanup steps for light droppings are easy to follow. DIY falls short with crawlspaces, rats, and hidden gaps. Norway rats burrow along foundations and get into crawlspaces, which are hard to inspect and seal without equipment. Rats also chew through weak repairs. Heavy deer mouse contamination in a closed shed is real exposure. A fair split: DIY for garage sealing and indoor mouse trapping, and a provider for crawlspaces, rats, and heavy cleanup.
Rodents in Spokane Valley
Spokane Valley was founded as a city in 2003 and is known as a Spokane suburb and for the Centennial Trail. About 106,000 people live in this suburban city, and garages, yards, and any crawlspaces are where most rodent work happens. The climate is warm summer continental at about 2,001 feet, with summer highs near 84F, winter lows around 23F, about 17 inches of precipitation, and humidity near 64%. Those cold winters drive house mice, deer mice, and Norway rats indoors from September through November, and they stay until spring. The drier climate means irrigated yards and pet bowls draw rodents close. The median home value is about $380,000, and damage to wiring, insulation, and stored items adds up. Washington health officials report infected deer mice throughout the state and 1 to 5 hantavirus cases a year, a reason to clean droppings carefully.
Local research
Rodents in Spokane Valley, WA: what the public record shows
Before you compare quotes, it helps to know which rodents actually live in Washington, when they are busiest around Spokane Valley, and what the state figures look like. Everything below links to the agency or university page it came from.
Rat litter size
Old World rats are not regulated; killing is unrestricted.
WDFWRat entry hole
Footprint about 1/2 inch long; incisors grow 5 inches a year.
WDFWRodent species recorded in Washington
- 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.
- Roof rat (Rattus rattus) — Climber of attics and trees in warm and coastal regions; tail longer 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 Spokane Valley
Year-round; roof rats in Puget Sound attics.
Rules that apply in Washington
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: Hantavirus; WDFW; CDC; Pest Notes: House Mouse; Pest Notes: Rats. Figures are quoted as the source prints them. How we check our sources
Simple ways to keep rodents away
- Seal gaps in August, before September's cold nights.
- Replace worn garage door bottom seals.
- Screen crawlspace and foundation vents with 1/4-inch hardware cloth.
- Store bird seed, pet food, and grass seed in metal cans.
- Fix dripping faucets and irrigation leaks near the foundation.
- Keep firewood off the ground and away from the house.
- Use sealed plastic bins in the garage instead of cardboard.
- Set a few traps in the garage at the start of fall.
Before you call, sketch where you have seen droppings or heard noise and measure any gaps you found. It makes the first visit faster and the quotes comparable.Did you know?
WDFW notes that a rat's front teeth grow about 5 inches a year, which is why rats gnaw constantly.
The CDC reports that 94% of U.S. hantavirus cases since 1993 were west of the Mississippi River.
Norway rats have 4 to 6 litters a year, and a single female can wean 20 or more young annually, per UC IPM.
Questions people ask
Are roof rats a problem in Spokane Valley?
Less than in Puget Sound. Washington's state data notes roof rats mainly in Puget Sound attics. Across Spokane Valley, the rodents you are most likely to deal with are house mice, deer mice, and Norway rats, which move into garages, crawlspaces, and walls in fall.
When do mice come into Spokane Valley homes?
Mostly September through November, as nights cool. With winter lows near 23F in Spokane Valley, mice that get in during fall stay in walls and garages all winter. Sealing gaps in August and setting traps early in fall catches them first.
Is hantavirus a risk around Spokane Valley?
Yes, though cases are rare. The Washington Department of Health says infected deer mice live throughout the state, with 1 to 5 cases a year and about 1 in 3 diagnosed people dying. Clean deer mouse droppings by ventilating, soaking with bleach solution, and wiping, never by sweeping.
How do I clean mouse droppings in a garage or shed?
Start by opening the garage or shed wide and leaving it for 30 minutes. Wear gloves. Soak the droppings with 1.5 cups of bleach per gallon of water and wait 5 minutes. Then wipe with paper towels, seal the waste in a bag, and give the spot a second spray.
How fast can rats multiply?
Fast. WDFW reports rat gestation of about three weeks, litters of 6 to 10 young, and young rats breeding at 3 to 4 months. A pair that gets into a crawlspace in fall can produce several litters before spring if entry points stay open.
Can I trap rats without a permit in Washington?
Yes. Washington does not regulate Old World rats such as Norway and roof rats, and WDFW lists killing them as unrestricted. Deer mice are native, but trapping them around your home is still the standard approach. If bait is used, ask for locked stations.
What size gap do I need to seal?
Anything around 1/4 inch or larger. WDFW notes rats can start through a 1/4-inch hole and chew it larger, and mice fit through the same size. In Spokane Valley homes, check garage door corners, utility entries, crawlspace vents, and dryer vents.
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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