The short version
Rodent control in Ann Arbor, Michigan comes down to three jobs: close every pencil-width gap before fall, trap the house mice already inside, and clean droppings the CDC way. Winter lows near 17F push mice and Norway rats indoors from late September, and Washtenaw County logged Michigan's first hantavirus case in 2021.
- Ann Arbor's 17F winter lows send mice indoors each fall; seal by early September.
- Michigan's first confirmed hantavirus case came from Washtenaw County in 2021.
- Michigan DNR recommends metal flashing or hardware cloth for holes, not foam alone.
- Never sweep droppings; soak them in bleach and water first.
This guide is for Ann Arbor homeowners hearing activity in walls, renters near the University of Michigan who keep finding droppings, landlords between leases, and anyone about to clear out a garage or shed.
What to look for
Summers near 83F and about 36 inches of yearly rain keep outdoor populations fed, so by late September plenty of rodents want a warm crack in your siding. Deer and white-footed mice move from fields into garages and wall voids when the weather turns. Norway rats burrow along foundations and sheds, then use basement gaps. Four rodents matter here: the house mouse, the Norway rat, the deer mouse and the white-footed mouse.
- 1Scratching in the ceiling the first nights the furnace runs.
- 2Rice-sized droppings in drawers or along the basement sill.
- 3Droppings near three-quarters of an inch by the garage, a Norway rat sign.
- 4Acorns or birdseed stashed in boots, a deer mouse habit.
- 5Fresh fist-sized holes along the foundation or beside the compost bin.
Why it’s worth acting soon
- Mice that slip in during October can raise several litters by spring.
- Gnawed wiring inside a wall is a fire risk you rarely see.
- Droppings left to build up in a shed make cleanup riskier.
- Norway rat burrows can undercut steps and slabs in one season.
2021, Washtenaw CountyMichigan's first confirmed hantavirus caseMichigan DHHS 40 percentHantavirus pulmonary syndrome fatality rateMichigan DHHS Treatment options and typical costs
Whole-house exclusion
Quoted after inspection
A provider closes foundation, utility and roofline openings with metal flashing, hardware cloth or steel wool, the durable materials Michigan DNR points to.
- Time
- Set after the exterior walk
- Best for
- Repeat fall mice
Indoor snap-trap program
Quoted after inspection
Traps go wherever droppings are fresh, and the provider returns to check and reset them. Ask how many follow-up visits are included.
- Time
- Until trap checks come back empty
- Best for
- Mice already inside
Exterior stations for Norway rats
Quoted after inspection
Tamper-resistant stations line the foundation and fence, spaced to cover the 100 to 500 feet a rat may travel from its burrow.
- Time
- Ongoing while burrows stay active
- Best for
- Rat burrows outdoors
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 get into Ann Arbor homes?
Four species show up in Ann Arbor. The house mouse can live its whole life inside your walls and pantry. The Norway rat is heavier, burrows beside foundations and compost, and slips into basements through low gaps. Deer mice and white-footed mice look almost identical, with brown backs and white bellies and feet. They summer in fields and woodlots and drift into garages when it gets cold. House mice and rats bring contamination and chewing, while deer mice also carry hantavirus.
A rodent calendar for Ann Arbor, season by season.
January and February are quiet outside but busy in your walls, because any mouse that got in last fall nests near the furnace while lows sit around 17F. March through May is cleanout season, and Michigan health officials note hantavirus exposure clusters in spring and summer. June through August, with highs near 83F, outdoor rodents breed hard, so book exterior repairs then. September through November is the main event in Ann Arbor, as rodents test every gap along the foundation and roofline before the first frost.
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.What the 2021 Washtenaw County case means for your cleanup.
Until 2021, Michigan had never confirmed a human hantavirus case. That year MDHHS reported a Washtenaw County adult hospitalized with Sin Nombre virus after cleaning an unoccupied, infested dwelling. The CDC has tallied 890 US cases from 1993 through 2023, mostly in western states, so the lesson is technique rather than panic. The virus spreads when dried droppings are stirred into the air. Air the space for 30 minutes, soak everything in a 1:9 bleach mix, then wipe and bag it while wearing gloves.
Sealing is the part that lasts in Ann Arbor.
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. In Ann Arbor, MI, 36 inches of rain a year and 72% humidity keep exterior wood soft, so gaps open again seasonally and need re-checking. Traps and bait remove the rodents you have; sealing removes the ones that would come in next.
What rodent control costs in Ann Arbor.
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. A simple kitchen mouse job is at the low end; a multi-floor rat colony with a sanitation cleanup is at the high end. In Ann Arbor, MI, the timing matters too — most activity starts in fall as 17°F winter lows push rodents indoors, which is when providers are busiest. Ask for the sealing and the trapping as separate line items, and what the re-service covers.
What affects the price
- How many entry points the exterior walk turns up.
- Whether soiled attic insulation needs removal and cleaning.
- Rats versus mice, since a Norway rat plan needs outdoor stations.
- Attached garages, crawlspaces and sheds needing their own sealing.
- How many return trap checks the plan includes.
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What's your biggest concern about rodents?
When to call for help
Call before you clean a shed or vacant unit with heavy droppings, too. Michigan's first hantavirus patient got sick after cleaning exactly that kind of space in Washtenaw County. Call a provider if you still catch mice after two weeks of trapping, find droppings bigger than a rice grain, or hear activity on more than one floor.
What you can do yourself
A provider earns the fee outside, at sill plates, siding seams, garage door corners and the roofline. Rats are harder, since a burrow system needs coverage across the whole yard. DIY handles a few house mice well. Snap traps with a pea-sized dab of peanut butter, trigger end against the wall, handle most small indoor problems.
Rodents in Ann Arbor
The city dates to 1824 and is an urban university and tech hub of about 120,000 people. Wherever buildings share walls, mice travel between units, so treating one apartment rarely ends the problem. Rodent pressure here peaks in fall and holds through winter, while hantavirus exposure tracks with spring and summer cleanouts. Ann Arbor sits at about 840 feet in Michigan's humid continental belt, with average humidity near 72 percent. Moist air and steady rain give mice easy water to go with the warmth they find indoors. In Ann Arbor, 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.
Local research
Rodents in Ann Arbor, MI: what the public record shows
Before you compare quotes, it helps to know which rodents actually live in Michigan, when they are busiest around Ann Arbor, and what the state figures look like. Everything below links to the agency or university page it came from.
Rodent species recorded in Michigan
- 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 Ann Arbor
Rodents push into Michigan structures in fall; hantavirus exposure clusters in spring and summer cleanouts.
Michigan had no confirmed human hantavirus case until 2021, so the routine risk is contamination and structural damage.
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: Michigan Department of Health and Human Services; 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 by early September, before the first cold snaps.
- Cap and screen the chimney, as Michigan DNR advises.
- Trim branches so no limb hangs within a few feet of the roof.
- Fence gardens with mesh that has openings of 1/2 inch or smaller.
- Keep birdseed and pet food in lidded metal cans in the garage.
- Replace a worn garage door bottom seal, a favorite white-footed mouse entry.
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?
About 94 percent of US hantavirus cases since 1993 came from west of the Mississippi, which made Michigan's 2021 case unusual.
A female Norway rat can have 4 to 6 litters a year and wean 20 or more young.
The CDC lists rat-bite fever, salmonellosis and tularemia among diseases rodents spread directly.
Questions people ask
When do mice start coming inside in Ann Arbor?
Most mice move into Ann Arbor homes from late September through November, as nights slide toward freezing. With winter lows near 17F they breed indoors all winter, so sealing in early September beats reacting in December.
Is hantavirus a real risk in Michigan?
MDHHS confirmed Michigan's first case in 2021, a Washtenaw County adult hospitalized after cleaning an unoccupied, infested dwelling. The state puts the fatality rate at 40 percent, with illness one to five weeks after exposure. Rare but real.
How do I clean up mouse droppings without getting sick?
The CDC says to air the space for 30 minutes, then soak droppings in 1.5 cups of bleach per gallon for 5 minutes. Wear rubber gloves and bag everything. Wet them, never sweep or vacuum.
Why do mice keep coming back after I trap them?
Trapping removes mice but leaves the door open. A mouse fits through 1/4 inch, so check pipes, dryer vents and the sill plate, then close them with metal flashing or hardware cloth.
What does rodent control cost in Ann Arbor?
Most providers in Ann Arbor quote after an inspection, based on entry points found, whether rats are involved and how many trap checks are included. Ask for each part as a separate line. There is no single local price.
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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