Learn how to tell carpenter ants from regular ants and when to call a professional in Plainfield, IL.
Most homeowners who call us about ants aren’t sure what species they’re looking at — and that’s understandable. But the difference between a carpenter ant and a pavement ant isn’t just academic. One is raiding your kitchen. The other is quietly hollowing out your deck posts, window frames, or floor joists. As a pest control company based in Plainfield, we see both regularly, and the treatment approach for each is completely different. Here’s how to tell them apart, what to look for, and when the situation calls for professional help.
When a homeowner spots a trail of small ants along the kitchen counter, the instinct is usually the same: grab a can of spray, wipe them out, move on. And for most common household ants, that reaction — while not ideal — isn’t going to result in structural damage to your home.
Carpenter ants are a different situation entirely. They don’t eat wood the way termites do, but they excavate it to build their nests, carving out smooth galleries inside structural lumber, deck framing, window headers, and anywhere else they find softened or moisture-damaged wood. Left untreated, a mature carpenter ant colony can compromise load-bearing wood in your home. We’ve seen floor joists so hollowed out that the wood crumbled when touched.
The treatment matters too. A bait system designed for pavement ants won’t eliminate a carpenter ant colony nesting inside your wall. The species determines the strategy — which is why accurate identification is the first step in any effective treatment.
Carpenter ants (Camponotus species) are the largest ants you’ll encounter in Illinois. Workers range from about a quarter inch to over half an inch long, and they’re typically solid black or dark reddish-brown. Their size alone usually gets homeowners’ attention — these aren’t the tiny ants you see on the sidewalk.
What makes carpenter ants destructive is their nesting behavior. Unlike most ant species that nest in soil, carpenter ants excavate wood to create their colony’s living space. They prefer wood that’s already been softened by moisture — a leaking window frame, a deck board that stays wet, the sill plate in a damp basement. Once they establish a parent colony, they’ll often create satellite colonies in other parts of the structure, expanding their reach through your home.
A mature colony can contain 10,000 to 50,000 workers and may take three to six years to reach full size. That timeline is important: by the time most homeowners notice carpenter ants, the colony has usually been active for at least a year or two. The damage you can see is almost always less than the damage you can’t.
One detail that often surprises people: carpenter ants don’t actually eat wood. They push the excavated material out of their galleries as a sawdust-like debris called frass. Finding small piles of fine wood shavings near baseboards, window sills, or in your basement is one of the most reliable signs of an active colony.
The ants most homeowners encounter in the Plainfield area aren’t carpenter ants — they’re one of three common species that nest outdoors and come inside looking for food and water.
Pavement ants are the small, dark brown ants you see trailing along driveways, sidewalks, and garage floors. They nest in cracks in concrete and foundation walls and are attracted to greasy or sweet foods. They’re a nuisance, not a structural threat.
Odorous house ants are slightly smaller and give off a distinctive rotten-coconut smell when crushed. They’re the most common kitchen invaders in our area and can form massive colonies with multiple queens — which is why squishing a few never seems to solve the problem. They nest in wall voids, under appliances, and in insulation.
Little black ants are exactly what they sound like: tiny, dark, and numerous. They tend to show up in late spring and summer, trailing along countertops and around pet food bowls. Like odorous house ants, they’re a food-motivated nuisance species.
None of these species damage wood. Their presence is annoying but doesn’t threaten your home’s structure. The concern is when homeowners assume every ant is “just a regular ant” and miss the signs of carpenter ant activity until the damage is significant.
You don’t need to be an entomologist to identify what’s in your home. A few key differences are visible to the naked eye and immediately useful.
Size is the fastest indicator. Carpenter ants are noticeably large — a quarter to half inch long, sometimes bigger. Common household ants like pavement ants and odorous house ants are typically an eighth of an inch or smaller. If the ant on your counter looks big enough to cast a shadow, pay attention.
Body shape matters. Carpenter ants have a smooth, evenly rounded thorax (the middle section between head and abdomen). Most smaller ant species have an uneven or bumpy profile in that same area. Under a magnifying glass or phone camera zoom, this difference is clear.
Where you find them tells a story. Small ants near food sources — kitchen counters, pantries, pet bowls — are almost always foraging species. Carpenter ants turn up in different places: near windows, along baseboards in bathrooms, around deck framing, emerging from behind trim or light fixtures. Finding large ants in these areas, especially in winter, is a strong indicator of a nesting colony.
Time of year is a clue. All ant species are more active in warm months, but carpenter ants are the only common species you’ll find active indoors during winter. A heated wall void makes a perfectly comfortable satellite nest, and workers will forage even when it’s freezing outside. Large ants in your home between November and March almost always mean a colony living inside the structure.
Carpenter ant colonies are usually hidden inside walls, under insulation, or within structural wood — so you rarely see the nest itself. But the colony leaves signs if you know what to look for.
Frass deposits. That fine, sawdust-like material near baseboards, window frames, or in basement corners is excavated wood pushed out of the nest. It often contains fragments of dead insects mixed in with the wood shavings. Frass is the single most reliable visual indicator of an active carpenter ant nest nearby.
Large ants in living spaces. Seeing one or two large black ants in your bathroom or kitchen during summer might be scouts. Seeing them repeatedly — or seeing them anywhere indoors during winter — means a colony is established inside your home. Heated wall voids and insulated attic spaces give satellite colonies a year-round environment.
Swarmers in spring. Winged carpenter ants emerging inside your home between April and June indicate a mature colony that’s been present for at least three to five years. Swarmers are reproductives leaving to start new colonies, and their presence indoors means the parent colony is inside the structure, not outside.
Faint rustling in walls. In quiet moments — usually at night — you may hear a soft rustling or crinkling sound inside walls near an active nest. Carpenter ants are primarily nocturnal, and a large colony excavating wood can produce audible sound.
Hollow or weakened wood. Tapping on window sills, door frames, or deck posts that sound hollow or feel soft can indicate internal galleries. By the time wood damage is detectable this way, the colony has usually been active for several years.
Carpenter ants need two things: moisture and wood. The Plainfield area provides both in abundance, which is why we treat more carpenter ant infestations here than almost any other pest.
Mature trees and wooded lots. Neighborhoods like Clublands, Grande Park, and the established areas along Renwick Road have large shade trees, many of which develop deadwood, hollow sections, or storm damage over time. These trees serve as parent colony sites. From there, carpenter ants send scouts into nearby homes looking for satellite nesting locations — and they don’t have to travel far when the tree canopy is close to the roof.
Decks and outdoor structures. The Plainfield area has a high density of homes with wooden decks, pergolas, and fence lines. Any outdoor wood that stays damp — posts set in soil, boards that don’t dry quickly after rain, ledger boards where the deck meets the house — is an open invitation. We see heavy carpenter ant activity in deck framing along the Heritage Corridor and in newer subdivisions where landscaping retains moisture against the foundation.
Seasonal moisture patterns. Illinois spring rains saturate soil and raise moisture levels in basements, crawl spaces, and exterior wood. By the time carpenter ants become most active in May and June, the conditions in and around Plainfield homes are ideal. Homes near the DuPage River corridor or in low-lying areas of Winding Creek and Settlers’ Park tend to see the earliest activity each season.
Construction and landscaping choices. Mulch beds pushed up against foundations, firewood stacked near exterior walls, and landscape timbers that hold moisture all create stepping stones between outdoor colonies and your home’s interior. These are common features in Plainfield yards — and common factors in the carpenter ant calls we respond to.
We understand the appeal of handling it yourself. A can of ant spray costs a few dollars, and it does kill the ants you can see. But with carpenter ants, the ants you can see are a fraction of the colony — the foragers. The queen, the brood, and thousands of workers are inside the wood, behind your walls, completely untouched by surface sprays.
Worse, most over-the-counter sprays are repellents. They don’t eliminate the colony; they just push it to relocate. Carpenter ants respond to chemical disruption by budding — splitting the colony and establishing new satellite nests in different parts of the structure. What started as one nest behind your bathroom wall can become three separate nests in the attic, basement, and garage. We’ve seen homeowners spend months spraying and re-spraying while the colony quietly expanded.
Professional carpenter ant treatment works differently. It starts with identifying every active and satellite nest location, which requires understanding their foraging patterns and knowing where to look. Treatment uses non-repellent products that workers carry back to the colony without detecting it — the same trophallaxis principle that makes baiting effective for other ant species, but applied to the specific challenge of a colony hidden inside structural wood. The goal isn’t killing the ants you see. It’s eliminating the colony you can’t.
We also address the conditions that attracted them: identifying moisture sources, recommending wood repairs, and sealing the entry points that gave them access. A carpenter ant treatment that doesn’t address the underlying moisture problem is just a temporary fix.
If you’re seeing large ants in your home — especially near windows, in bathrooms, or during the colder months — don’t wait to find out whether they’re carpenter ants the hard way. Sanctuary Pest Control offers free carpenter ant inspections for homeowners in Plainfield and the surrounding area. We’ll identify the species, assess the situation, and give you a straightforward recommendation.
Call us today at 815-993-3472 or book your inspection online.
Sanctuary Pest Control is a family-owned company headquartered in Plainfield. We’ve been protecting homes in this community since 2016 — and carpenter ants are one of the things we know best.
