There’s a world beneath your porch—and it’s not a place for the faint of heart.
At Pest UnHABITAT, we’ve crawled into the shadows so you don’t have to. Under crawlspaces, decks, and porches, we’ve uncovered rat dens, forgotten tunnels, and, on more than one occasion, nests buzzing with territorial bumblebees.
Hopefully, if anything’s living under your structure, it’s a family of rabbits—and not the kind of tenants who chew wires, undermine foundations, or leave a stink. When rats move in, they don’t always stay outside. One of the nastier outcomes is when outdoor rat presence leads to a full-blown infestation indoors—whether it’s a home, restaurant, or business.
And a word of caution: just because you can fit under your deck or into a crawlspace doesn’t mean you should. These spaces are confined, dusty, and sometimes dangerous. If you’re not equipped with PPE—like a respirator and disposable overalls—it’s safer to call a professional.
Skunks Don’t Warn You. Bumblebees Buzz First.
Crawlspaces might seem quiet from above. But dipping your head below the structure can reveal more than just cobwebs. It’s not always safe down there. Skunks often live in the shadows under decks or sheds, and they rarely announce themselves. The absence of a foul odour is no guarantee—they typically spray away from their dens, not in them. That said, if provoked or cornered, they can still spray for self-defense. Just because you can’t smell a skunk doesn’t mean one isn’t living quietly underneath.
Bumblebees are another kind of surprise. They usually mind their own business—unless you’re near their hive. Then, their mood can shift quickly. When disturbed, their buzzing takes on a distinctly angry pitch. It comes in short bursts—starting and stopping in brief choppy pulses. When you hear it, you know something’s about to go down. Unlike honeybees, whose barbed stingers get stuck after a single sting, bumblebee females can sting repeatedly—and will if they think their nest is in danger.
It’s the females who do the stinging, while male carpenter bees act like bodyguards—chasing intruders without actually having stingers. We mention carpenter bees here because they’re also large and often mistaken for bumblebees, but their behaviour is quite different. You’re unlikely to find carpenter bees under porches or crawlspaces—they usually prefer to nest higher up in wood trim, soffits, or beams.
If you’re curious about the difference—especially how carpenter bees defend their nests and how painted wood does (or doesn’t) factor in—check out our related post: Do Painted Surfaces Stop Carpenter Bees?
We’ve also encountered bumblebees—and even wasps—setting up shop in old rodent burrows. These ready-made cavities offer dry, protected spaces that can attract more than just mammals.
Of Burrows and “Chicken Nests”
Rats are skilled excavators. With motion-triggered trail cameras, we’ve seen them move shocking amounts of soil overnight—sometimes enough to rival what a groundhog displaces. The visible hole—often 2 to 3 inches (5 to 7.5 cm) in diameter—is just the beginning. When this kind of opening is paired with a surrounding mound of soil, it’s a likely sign of rat tunneling. (Shallow holes of the same size without mounds may be from squirrels or other animals digging for different purposes.)
Not all rat holes go deep—some are just shallow paths to slip under fences. But when rats dig in, they sometimes establish dens beneath hard surfaces like concrete slabs used for patios, steps, or the lining around decks. Homeowners and businesses sometimes install pavers thinking it will keep animals out—and the intention is right. But when hardscaping isn’t installed with proper base layers and gravel depth, these slabs can become an attractive “roof” for rats excavating underneath. Concrete is more durable than asphalt, but over time, even slabs can crack and shift.
We’ve encountered multiple cases of soil collapse beneath structures like decks and crawlspaces where rats had been active. These depressions typically span up to 1 metre wide (2 to 3 feet) and are up to several inches deep—very similar to the size and shape of typical potholes. When weight is applied—someone steps on the area, or rain loosens the soil—the den beneath gives way.
In one case, a crawlspace too tight for a human to inspect directly showed signs of rat activity—and even hosted a bumblebee hive. That same property had a pothole on the adjacent paved driveway that matched the dimensions we’ve seen in collapsed rat dens elsewhere. It was one more piece of circumstantial evidence suggesting a possible link between subsurface rat activity and depressions above.
Pothole-like formations near structures are often attributed to natural causes—erosion, settling, water damage. And yes, they often are. But in neighbourhoods where rats are present and aging sewer systems run parallel to the street, it’s worth asking whether rat activity may be contributing to the problem.
In French, potholes are called nid de poule—literally, “chicken nest.” It’s a humorous and oddly affectionate name for something as disruptive as a pothole. But when you’ve seen what rats can do to soil structures below the surface, you start to think: maybe “rat’s nest” is the more accurate label in some cases.
Old Sewer Lines, New Rat Homes
We often find burrows in properties with older plumbing systems. A rusting metal cleanout cap is a visible clue—but the bigger issue lies underground. Older sewer connections often used metal piping, which corrodes and rusts over time. Cracks in these buried lines can offer rats direct access from the sewer into the yard—or toward the building foundation. (Newer lines tend to use white plastic, which is far more resistant to corrosion.)
Telltale Signs That Need Immediate Attention
Whether you own a home, restaurant, or commercial building, the following issues should be addressed quickly:
- Fresh soil mounds near fences, foundations, decks, patios, porches, or sheds
- A bald patch of earth near any of those structures
- A hole about 2 to 3 inches (5 to 7.5 cm) in diameter that leads into a deeper tunnel (not just a shallow hole)
- Trash—food wrappers or condiment packs—dragged beneath structures or left near entry points
- A pile of crushed snail shells
- Droppings that resemble mouse droppings but are larger—elongated like grains of rice, but longer and thicker, usually black or dark brown—clustered in a single spot (a latrine)
- Cobwebs with visible sawdust, especially under porches or decks—this may point to Carpenter Ants, which are unrelated to rats but demand immediate attention due to the structural damage they can cause
- A space—deck, porch, crawlspace, shed, or garage—that hasn’t been accessed or inspected in years
- Or soft, uneven ground that gives way underfoot—like a small sinkhole forming
What Responsible Property Owners Should Know
While these signs call for urgent attention, prevention is even more valuable. At Pest UnHABITAT, we strongly encourage every home or business owner—including homeowners, landlords, and restaurant operators—to schedule regular assessments and inspections. For homeowners, a thorough check every spring and fall helps catch early signs of pest or wildlife activity—before the damage begins. For businesses and restaurants, more frequent inspections are often necessary due to higher risks and regulatory standards.
Preventive exclusion work—before animals or insects move in—helps avoid costly repairs, health risks, and stressful conflicts with wildlife. It’s not just smart property management—it’s environmental stewardship, too. By intervening early through repairs, exclusion, and strategic planning, we may avoid the need for pesticides or the unnecessary removal of wildlife that’s simply looking for shelter in the wrong place.
If you’d like to protect your structure before problems arise—or even just want peace of mind—contact us to send a message or give us a call. You can simply write something like “Requesting a regular inspection for prevention” in your message, and please include your address so we can better assist you.
If you found this post helpful, please consider sharing it with a friend or neighbour. Many people have porches, crawlspaces, sheds, or patios that haven’t been checked in years—sharing this may help them catch issues early or prevent them altogether.
And if you’re lucky, the only thing hiding under your porch will be a quiet family of rabbits—no pests, no damage, just a fluffy reminder that not all surprises are bad ones.