From Astor Street Mansions to North Branch Rowhomes: Near North Side Pest Control

Chicago's most crowded square miles, built in layers since the 1780s

The first known permanent settlement at Chicago stood here, near today's Michigan Avenue Bridge, where Jean Baptiste Point du Sable built a trading post in the 1780s. Two centuries of rebuilding followed. Mansions rose around Rush and Erie, then the wealthy moved north after Potter Palmer built his castle on Lake Shore Drive in 1885 and the Gold Coast took shape. Factories and forges filled the riverfront blocks known around 1900 as Smokey Hollow. Postwar towers climbed along the lake, and public housing came and went on the west side near the river.

Today the community area covers only about 2.72 square miles, yet in 2020 it passed Lake View as Chicago's most populous, and at roughly 39,500 residents per square mile it is also the most densely settled. For pests, that density and that layering are everything. A 130-year-old greystone shares an alley with a 50-story tower, and a timber loft stands a block from new townhomes. Each building type leaks in its own way, and the animals that exploit them move freely between them.

House mice behind limestone, brick and plaster

Across the older housing stock, the most frequent call is for house mice. A limestone front or a brick party wall looks solid from the street, but these buildings have been changed over and over. Coal chutes were bricked shut, gas lighting lines were abandoned, steam heat gave way to forced air and kitchens moved up from the basement. Every change left a void, a patch or a pipe sleeve that never quite closed. Mortar at grade, soaked by snowmelt and road salt every winter, slowly opens gaps a young mouse can squeeze through.

Inside, mice follow the original service routes. Plaster on wood lath leaves hollow cavities from basement to attic, and dumbwaiter shafts, laundry chutes and back stairs connect the garden level to the bedrooms upstairs. In row houses the shared party wall has openings at each floor where joists bear into the brick, so a neighbor's mice become yours. In River North's converted lofts, seasonal movement of heavy timber floors leaves hairline gaps along brick walls and around beam pockets, and soffits built during conversion link one kitchen to the next.

Lasting control is mostly exclusion. A technician maps droppings and rub marks from the bottom of the building up, then seals with copper mesh, masonry-compatible patching and sheet metal. Snap traps and enclosed stations remove the mice already inside. Poison is used sparingly in plaster-walled houses, since a mouse that dies in a wall cavity three floors up can leave an odor for weeks.

Norway rats along the North Branch and the Goose Island canal

The western edge of the community area follows the North Branch of the Chicago River, and Goose Island sits inside it, a roughly 160-acre island created when a canal was cut in 1853. Seawalls, riprap, weedy banks and large non-residential parcels along both channels give Norway rats cover, water and room to dig. From there rats move east at night into the townhome rows and walk-ups along Division, Larrabee and Halsted, burrowing under patios, along fences and beneath trash pads.

Look for smooth, fist-sized holes with packed soil at the entrance, worn runways in grass along a foundation, gnawed cart lids and greasy smudges at the base of garage doors. Activity jumps after heavy rain raises the river and whenever a nearby lot is excavated. Locked bait stations along fence and foundation lines, packed or gravel-filled burrows and tight garage door seals are the standard response, and they work best when a whole row or development is treated together rather than one yard at a time.

Raccoons, squirrels and the alley behind the coach house

The south end of Lincoln Park sits just across North Avenue, and its mature trees feed a steady supply of raccoons, gray and fox squirrels, and Virginia opossums into the neighborhood. They travel the narrow alleys behind Astor Street, State Parkway and Dearborn, where brick coach houses that once held carriages now serve as garages and guest apartments. Raccoons climb downspouts and overhanging limbs to reach coach house roofs, then tear into soffits and attic vents. A female denning in April usually means kits by May, so removal has to be timed so young are not left behind.

Squirrels chew into cornices, roof dormers and the wooden trim of older houses, nesting in late winter and again in late summer. Opossums and the occasional striped skunk settle under decks and stoops in the townhome blocks near the river. Wildlife specialists confirm the animal, remove it humanely, then close the opening with heavy-gauge mesh or metal. Trimming limbs back from rooflines and keeping coach house doors shut at night removes much of the draw.

Two quieter problems: wool-eating moths and lake-fed spiders

Large Gold Coast homes and co-op apartments, with deep closets, cedar that has lost its scent and wool rugs in rooms that sit unused for months, suit webbing clothes moths and carpet beetles. Both feed on keratin in wool, silk, fur and feathers. Damage often surfaces only when winter coats come out in November or a rug is lifted during renovation. Pheromone traps confirm the species and point to the source, which is often one forgotten blanket or fur collar. Vacuuming, laundering or cold storage and targeted treatment of closet edges follow.

East of Michigan Avenue, the issue is the lake. Each spring, non-biting midges rise from Lake Michigan and gather on lit windows, and bridge spiders build orb webs across Streeterville balconies to catch them, sometimes dozens of floors up. They do not bite people or invade apartments, but the webs and spotting on glass are a real cleaning burden. Balcony perimeter treatments and warmer-toned exterior bulbs keep the numbers down.

Six building types between the river and the lake

Because the housing stock varies block by block, the best predictor of a pest problem here is the building itself. A provider who asks what kind of building you live in, which floor and which way the windows face is collecting the information that matters most. The list below sorts the common types by what local providers find in them most often.

Some buildings combine two types. A coach house behind a Gold Coast mansion has its own rodent and raccoon exposure apart from the main house, and a tower with townhouse-style units at its base gets rat pressure on the ground floor that the upper floors never see. Renovation history matters too. A greystone gutted and rebuilt in the 1990s may be tighter than its neighbor, while a loft whose kitchen was moved twice can hide several abandoned pipe openings behind new cabinets. Telling the provider what work has been done, and when, often shortens the search for the entry point.

• Gold Coast mansions and greystone row houses: mice through old masonry and party walls, raccoons and squirrels in cornices and coach houses
• Prewar co-ops along the lake: mice in service shafts, moths and carpet beetles in deep closets
• 1960s and 1970s concrete towers: German cockroaches in chute rooms and plumbing stacks
• Newer glass towers: move-in roaches, balcony pigeons and spring spiders
• River North timber lofts: mice in soffits and beam pockets, silverfish in garden units
• Townhome rows near the North Branch: rats under patios, mice under garage doors, opossums under decks

The year on the Near North Side

February through April is denning season. Raccoons and squirrels move into attics, coach houses and cornices, and pigeons start nesting on tower balconies and loft fire escapes. Spring rain pushes ants into garden-level kitchens and house centipedes out of damp basements. Late May and June bring the lakefront midge hatch and the wave of spider webs that follows it on east-facing glass.

Summer belongs to rats, along the river, in the alleys behind the coach houses and around construction on the remaining open parcels west of LaSalle. From late September onward, mice begin testing foundations and rear service doors, and calls climb into December. That is also when moth damage gets noticed as wool comes out of storage. January and February suit whole-house exclusion and riser sealing, since activity is concentrated indoors and easy to trace. Owners who winter elsewhere should arrange an inspection before leaving, because a closed house gives mice months without disturbance.

Prevention for masonry homes, lofts and towers

These steps target the specific weak points of the community area's building types. Owners of single homes can handle most of them, while co-op and condo residents should share the list with the building engineer, since many of the openings sit in common spaces. Work through it each fall before mice move indoors, and again in late winter before wildlife starts denning.

• Repoint soft mortar at grade with a mortar matched to the original rather than stuffing gaps with foam
• Seal abandoned coal chutes, gas line openings and old dumbwaiter and laundry chute shafts at the basement level
• Fit chimney caps and screen attic and soffit vents on houses and coach houses
• Trim tree limbs at least six feet back from rooflines near the park
• Keep alley carts lidded and coach house doors closed at night
• Rotate stored wool and furs and keep them in sealed garment bags
• Close pipe gaps behind kitchen cabinets in lofts and towers and report sticking chute doors
• Ask the association to treat the whole townhome row for rats, not just one yard

Landmark districts, co-op boards and what a visit involves

Several protected districts sit inside the community area. The Astor Street District has been a Chicago Landmark since 1975, the Washington Square District around the city's oldest surviving small park was designated in 1990, and much of the Gold Coast is listed on the National Register. Inside a city landmark district, exterior work that needs a permit goes to the city's preservation staff. Trapping, baiting and interior sealing do not, but a new chimney cap, a replaced attic vent or bird deterrents on a cornice can. Experienced providers choose reversible, visually quiet methods, such as copper mesh behind existing grilles and dark-finished caps.

For a house, expect the technician to start outside, walking the areaway, gangway, rear garden and coach house before heading to the basement and attic, since the entry point is often far from the droppings. In a co-op or tower, the visit runs through management: insurance on file, a booked service elevator and, for building-wide problems, a board decision to hire one provider for every affected unit. For an animal in a coach house or mice in a kitchen, a technician can often come the same day, schedules permitting.