Pest Control in Stillwater, Minnesota

Minnesota’s birthplace, built by lumbermen on still water

The Washington County Historical Society traces Stillwater to 1840, when Joseph Renshaw Brown set up a small warehouse at the head of Lake St. Croix to supply his upriver fur trade. The real town came a few years later. John McKusick and three partners formed the Stillwater Lumber Company and had a sawmill running by spring 1844, powered by a creek diverted through a lake on top of the bluff. McKusick named the settlement after Stillwater, Maine, and later became its first mayor.

When the town was platted in 1848 it had about 600 residents, nearly all of them lumbermen. That August, with Wisconsin newly admitted as a state and the land to its west left without a government, delegates met in Stillwater and appointed Henry Sibley to ask Congress to organize Minnesota Territory. That meeting, the Stillwater Convention, is the source of the city’s claim to be the birthplace of Minnesota. The territory followed on March 3, 1849, and Stillwater was incorporated as a city on March 4, 1854.

The lumber boom that followed shaped the houses many Stillwater families live in today. The historical society describes a golden age of lumber-baron mansions, an opera house and brick commercial blocks on Main Street; the population reached 13,700 by 1884. After the mills closed, it fell to around 7,000 in 1940 and did not return to 13,000 until about 1980, when suburban growth had filled in planned neighborhoods west of downtown. The result is a city with two very different kinds of housing, and two different sets of pest questions: nineteenth-century homes near the river and bluffs, and newer subdivisions built around ponds, lakes and stormwater basins.

The river, the lakes and the creek: where Stillwater mosquitoes start

The St. Croix. The river in front of downtown is part of the St. Croix National Scenic Riverway. The National Park Service lists its designation date as October 2, 1968, with the lower river added on October 25, 1972. Together the St. Croix and Namekagon rivers form more than 200 miles of protected water. For a Stillwater homeowner, though, the practical mosquito questions are about standing water and shade on the lot itself.

Lily Lake. The Minnesota Board of Water and Soil Resources describes Lily Lake as a 41-acre lake in the heart of Stillwater, bordered by a small city park with a fishing pier. It was listed as impaired for aquatic recreation in 2002 after years of untreated runoff, and after two decades of work by the Middle St. Croix Watershed Management Organization, the city and volunteers, it came off the impaired waters list in 2022. Clarity jumped after a 2022 alum treatment, and water lilies and other aquatic plants came back with it. Board staff note that some residents mistake that growth for a problem; it is a sign of a healthier lake.

McKusick Lake and Brown’s Creek. The Minnesota DNR lists McKusick Lake, in McKusick Park, at 12 feet deep and warns that fishing from shore can be difficult in places because of cattails and other vegetation. Brown’s Creek runs from near Withrow to its mouth north of Stillwater; the DNR stocks 1,000 rainbow trout yearlings in it each spring and describes its lower reach as a steep, heavily wooded ravine.

Hundreds of small wet spots. The same Board of Water and Soil Resources report counts 336 rain gardens built by private landowners and the city, plus 235 storm drains adopted by volunteers. A rain garden is meant to drain between storms. The Metropolitan Mosquito Control District’s rule of thumb is that water standing for more than three days after a rain can produce mosquitoes, so a rain garden, low spot or clogged drain that stays wet longer than that is worth a closer look.

What the Metropolitan Mosquito Control District covers in Washington County

Stillwater is already inside a regional public mosquito program. The Minnesota Legislature created the Metropolitan Mosquito Control District in 1958, and Washington County was one of its original counties. The district now serves seven metro counties, about 2,900 square miles and more than 3 million people.

Most of that work targets larvae before they can fly. Crews apply Bti, a naturally occurring soil bacterium, and methoprene, an insect growth regulator. Small sites are treated by hand, and sites larger than three acres by helicopter. Adult mosquito treatments are a supplement, done after sampling shows numbers above a threshold, and mostly in high-use parks and recreation areas, at public events, or in response to resident complaints.

The limit Stillwater homeowners most often run into is written into MMCD’s own FAQ: the district does not spray private property unless there is a threat of mosquito-borne disease in the area. It may treat when numbers are extremely high and more than one household would benefit, but a routine barrier spray around one deck on the bluff is not part of the public program. MMCD also asks residents to call first, at (651) 645-9149, to have a wetland evaluated, because a deep pond with a thin fringe of cattails frequently needs no treatment at all.

Before paying for a mosquito treatment in Stillwater

MMCD’s resident guide lists the backyard sources its field staff find most often. Walk the property with this list first; a licensed company will ask about the same things:

• Anything that holds water past three days. Tarps over boats and firewood, sandbox covers, wheelbarrows, kids’ toys and flowerpot saucers.
• Bird baths. Change the water at least once a week.
• Decorative ponds. Keep the water moving, add fish, or use a larval control product labeled for that use.
• Old trees. Rot holes in large shade trees can hold water all summer.
• Gutters and rain barrels. Clear gutters in spring and fall and screen barrel openings.
• Tires. MMCD picks up tires without rims at no charge.
• Tall grass and dense shrubs. Adults rest there during the day. MMCD suggests mowing to under 2 inches and thinning overgrown shrubs.

If a yard still has too many mosquitoes after that, MMCD’s guidance is to hire a licensed professional rather than improvise with adult mosquito products, many of which can harm pollinators and fish when misapplied — a real concern on a lot that drains toward Lily Lake, McKusick Lake or the St. Croix. That is where Exterminator Dispatch routes the request to a company holding the correct Minnesota mosquito license.

Bats in lumber-era houses

Stillwater’s second most distinctive pest call comes from its oldest buildings. The Minnesota DNR says Big Brown Bats are the state’s most common bat, are often found in urban areas, and are the only Minnesota species that hibernates inside buildings. Little Brown Bats also use buildings in summer. Female bats form colonies from May through August to raise one pup each, and return to the same roost year after year, favoring attics, eaves and other tight, sun-warmed spaces.

The DNR is specific about how they get in: bats cannot chew through siding or create openings, so they depend on damaged or worn exteriors that are no longer weather-tight, and they fit through gaps as small as half an inch. Signs of a colony include stained entry points high on the building, scratching or squeaking in the walls, and bats leaving at sunset. A bat turning up in the living space every August often means young bats are exploring for an exit.

The DNR’s answer is exclusion: one-way devices over the entry points so bats can leave but not return, followed by permanent sealing. It should be done in early spring or fall, avoiding the May to August pup season, and not in winter, when bats are dormant and will not leave. Trapping or killing bats, the DNR says, is never an acceptable solution. When a Stillwater caller describes bats in the attic, the request is routed to a licensed company that performs exclusion work and follows that calendar.

Mice and carpenter ants in older foundations and framing

University of Minnesota Extension notes that mouse and squirrel activity picks up as fall approaches and that mice can fit into the tiniest spaces, so its advice is to seal cracks and holes in foundations, siding and similar gaps. Extension also cautions that poison bait can reach cats, birds and other animals that eat poisoned mice.

Carpenter ants are the insect counterpart. Extension describes them as nesting in moist or rotting wood, including in walls and under roofing, and chewing it into galleries rather than eating it. In an older home the real fix usually includes finding the leak or rot that attracted them; Extension notes that control typically requires a pest management professional.

ZIP codes served

Most Stillwater street addresses use 55082, a ZIP that also reaches into surrounding townships. Give your ZIP and street when you call, and the request is routed to a licensed company already working that part of the St. Croix Valley.

Verifying that a Stillwater exterminator is actually licensed

Two different Minnesota licenses matter here, depending on whether the job is inside the house or out in the yard.

Inside and on the structure (mice, ants, bats, bed bugs, cockroaches). The Minnesota Department of Agriculture requires anyone applying pesticides or using devices to control pests in, on or around structures for hire to hold a Structural Pest Control Applicator license and to work for a licensed Structural Pest Control Company. Applicators begin as Journeymen and may qualify as Masters after two years. Each company must employ at least one licensed Master, carry workers’ compensation and meet financial responsibility requirements. Structural licenses expire December 31.

Yard mosquito and tick treatments. MMCD’s resident guide directs homeowners to the MDA License Lookup with the license type set to Commercial Pesticide Applicator – Mosquitoes, Black Flies, and Ticks. For Stillwater, set the county to Washington. Ask for the company’s legal name and the applicator’s name and search both. Companies that Exterminator Dispatch routes Stillwater calls to are expected to hold the license that fits the job, and every caller is free to check.