What are opossums, and what makes them a problem here?
The opossum is the odd one out among Northeast Wisconsin’s nuisance wildlife, and knowing what it actually is takes a lot of the alarm out of a sighting while keeping the real concerns in focus. The Virginia opossum (Didelphis virginiana) is North America’s only marsupial — the females carry their young in a pouch — a cat-sized, grayish-white animal with a long, pointed pink nose, thin naked ears, a naked prehensile tail, and a mouthful of fifty teeth it bares in a dramatic hiss when cornered. That display, and the famous “playing dead,” are the whole of its defense. Opossums are not aggressive, they’re slow and nearsighted, they rarely stand and fight, and they’re a genuinely low rabies risk. What they are is opportunistic: a wandering scavenger that will move into any ready-made den near an easy food source and stay as long as both hold out.
Around Clintonville, opossums are near the cold northern edge of their range, and that matters more than it sounds. They don’t hibernate and they don’t handle hard winters well — their naked ears and tail are prone to frostbite — so in our climate a sheltered, slightly-warm den is a survival requirement, not a luxury. That’s exactly why they crowd in under decks, porches, sheds, and outbuildings, and into barns and crawl spaces, especially as the cold sets in. An opossum under your deck isn’t there to menace anyone. It’s there because your structure is warm and something nearby is feeding it.
Because BugBoss does both pest control and wildlife removal, we handle opossums as a complete job — the animal, the den, the food draw, and the parasite-and-droppings cleanup — rather than trapping the animal and leaving an open, scented crawl space and a coop still standing wide open. With opossums the follow-through is the whole point, because the animal itself is easy to remove; keeping the next one from taking the same den is the part that takes doing.
Wisconsin biology and behavior
Opossums live fast, wander widely, and improvise, and their habits around homes follow directly from that.
They are nocturnal omnivores and scavengers with a famously indiscriminate diet: insects, slugs, worms, carrion, small animals, eggs, fruit, and — around people — garbage, pet food, compost, birdseed, and whatever a chicken coop offers. They don’t establish a fixed territory the way many mammals do; a young opossum in particular drifts from den to den, using a cavity for a few nights and moving on, which is why opossum problems can seem to come and go. But a den with reliable food beside it will hold an opossum for the season.
Crucially, opossums rarely dig their own dens. They take over an existing cavity — very often an abandoned skunk or woodchuck burrow under a deck, shed, or slab, or a hollow, a brush pile, a woodpile, or a gap into a barn or crawl space. This is a direct link to the region’s other ground-denning wildlife: clear a groundhog from under your shed and leave the burrow open, and an opossum (or a skunk) may move straight into the vacancy. It’s one more reason closing a burrow matters as much as removing the animal that dug it.
Reproduction is pure marsupial. After a very short gestation the tiny, undeveloped young crawl into the mother’s pouch, where they nurse and develop for weeks before emerging to ride on her back as she forages. A female in Wisconsin may raise young from spring into late summer, sometimes two litters in a good year. The practical upshot is the same as with the region’s other spring-and-summer denning wildlife: a female removed carelessly can leave dependent young behind, so the timing and the handling matter.
Opossums do not hibernate and stay active all winter, which is a hard life this far north. In the coldest stretches they hole up in the most sheltered den they can find and live off fat reserves, emerging to forage on milder nights, and they suffer frostbite damage to ears and tail in severe cold. That drive for winter shelter is what pushes them under heated structures and into barns and crawl spaces from late fall onward. Their lifespan is short — often just two to three years in the wild — and their populations turn over fast, so the individual under your deck this winter is unlikely to be the same one next winter, but the den will keep drawing new arrivals until it’s closed.
When are opossums active in Northeast Wisconsin?
Spring brings breeding and the first pouch-young, and dispersing yearlings looking for dens and food after winter. A female denning under a deck in spring may be carrying young, which changes how removal has to be timed.
Summer is peak foraging and the season when mothers travel with young riding on their backs. Gardens, compost, fallen fruit, pet food, garbage, and coops all pull opossums in close, and a property with easy food will host them steadily.
Fall is when the search for winter shelter intensifies. As nights cool, opossums start settling into the dens they’ll try to overwinter in — under decks, sheds, porches, and into barns and crawl spaces — so this is a common time for one to move in under a structure.
Winter is the hard season and the one that drives opossums hardest toward your buildings. Unable to hibernate and vulnerable to frostbite, an opossum will hole up in the warmest sheltered den it can find and ride out the cold, emerging on mild nights. A crawl space, a barn, or the void under a heated part of the house is prime, which is why winter den complaints are common here despite the cold.
Around Clintonville and the surrounding rural towns, the vulnerability is the same mix that draws skunks and woodchucks: abundant ground-level cavities under decks, porches, sheds, and outbuildings; abandoned burrows waiting to be adopted; and easy food from gardens, compost, garbage, feed, and coops. The cold-edge climate simply sharpens the animal’s need for shelter, concentrating it around structures.
Local den sites
Opossums den wherever there’s a ready cavity and food nearby, and on properties here the same spots recur. The crawl space under a deck, porch, or stoop is the classic, especially when a skunk or woodchuck dug the entrance first. Sheds and outbuildings on skids or blocks, and on farms the barn, pole barn, granary, corn crib, and machine shed, all offer sheltered dens — and opossums readily den inside barns and outbuildings, up in stored hay or equipment, not just underneath. Abandoned skunk and woodchuck burrows under slabs, stoops, and structures get adopted wholesale. Woodpiles, brush piles, and junk piles in the yard or at field edges make natural dens. And chicken coops are both a den option and a food source in one, which is why coops draw opossums so reliably on rural properties.
The tell is usually an existing hole under a structure that an opossum has taken over — you may not see fresh digging, because it likely didn’t dig it — along with droppings and a musky (not skunk-strong) odor near the entrance.
Signs of an opossum
Opossums leave a scattered set of signs. Droppings are one of the clearer ones — large, dog-like, often found near feeding spots — and their presence in a barn or feed room is a specific concern on horse properties (see below). Look for raided garbage and pet-food dishes, disturbed compost, tipped or emptied bird feeders, and coop damage — missing or broken eggs, killed birds, cleaned-up spilled feed. A den entrance under a deck, shed, porch, or slab, frequently an adopted burrow rather than fresh digging, marks where it’s sheltering.
Tracks are distinctive: the hind foot shows an opposable, thumb-like toe set off at an angle, unlike any rodent or canine print. And you may simply see the animal at night — cat-sized, grizzled grayish-white, with a pointed pink nose, thin naked ears, and a long, scaly, naked tail, moving slowly and deliberately. If cornered it’ll hiss with its mouth wide open showing all those teeth, or it may keel over and “play dead” — both are defensive bluffs, not signs of aggression or, in the case of playing dead, of a sick animal. On rural properties, a persistent flea problem that keeps resurging despite treatment can itself be a sign of a wildlife den under a structure.
Health and property risk
Opossums carry a lighter health load than raccoons or skunks, and it’s worth being accurate about the parts that matter.
Rabies is a low risk. An opossum’s body temperature runs lower than most mammals’, which makes it a poor host for the rabies virus, so rabies in opossums is genuinely uncommon — not impossible, so an animal that’s staggering, disoriented, or unnaturally tame still deserves distance and a call, but you should not assume a rabies threat from an opossum the way you would from a skunk or raccoon.
Fleas and ticks are the routine concern. Opossums carry fleas, ticks, and mites, and they transport them right into your yard and under your deck. There’s a popular belief that opossums are a tick-control ally because they groom off and eat the ticks that latch onto them — and they do eat some — but recent field research has walked back the dramatic numbers from an early lab study; wild opossums eat far fewer ticks than that figure suggested, and examined opossum stomachs rarely contain ticks at all. The honest bottom line is that an opossum denning by your house is a net source of fleas and ticks, not a solution to them, and in a region with the tick and Lyme pressure this one carries, that’s not trivial.
Droppings carry bacteria. Opossum feces can harbor leptospirosis (spread through contaminated soil and water) and salmonella, so den debris and droppings are handled with gloves and sense, not swept up bare-handed.
Horses face a specific risk. Opossums are the definitive host of Sarcocystis neurona, the parasite that causes equine protozoal myeloencephalitis (EPM) — a serious neurological disease horses can develop after eating feed or drinking water contaminated with opossum droppings. On horse properties, keeping opossums out of the barn, feed room, and hay storage, and cleaning up their droppings, is a real herd-health measure, not just tidiness. This is a big reason opossum work on rural and equestrian properties emphasizes securing feed and outbuildings.
Property damage is modest compared with a woodchuck or raccoon. Opossums don’t excavate their own burrows and don’t tear up structures the way a raccoon does; the harm is mostly the coop raiding, garbage and garden mess, droppings, and the parasite load, plus occasional damage getting into a barn, crawl space, or feed store. The indirect problem is the same as with the other ground-denners: an opossum keeping a crawl-space den open and scented helps keep that den attractive to whatever comes next.
Why doesn’t DIY work on opossums?
Homeowners try the familiar remedies on opossums, and they fail for the same structural reasons they fail on skunks and woodchucks.
Repellents and harassment — mothballs, ammonia rags, predator-urine granules, lights, radios — are unreliable and short-lived. They might annoy a drifting opossum into leaving for a night, but they do nothing about the open den or the food that drew it, so the animal or the next wanderer returns. Mothballs scattered under a deck are also a pesticide being misused, and they contaminate soil for no lasting benefit.
Sealing the void without removing the animal traps whatever’s under there — and in spring or summer, a female with pouch or back young, which then die in an inaccessible space and become an odor-and-cleanup problem. The den has to be confirmed empty, and young accounted for, before it’s closed.
Trapping alone ignores the two things that actually solve it: closing the ready-made den and cutting the food. Trap the opossum and leave the burrow open and the coop and garbage accessible, and you’ve cleared one drifter while leaving a furnished, stocked den for the next — often within weeks, since opossums move den to den. And there are Wisconsin handling and relocation rules to follow even for a lightly protected animal; hauling one off to dump elsewhere isn’t the clean fix people imagine.
Leaving the coop and feed open is the rural version of the mistake. As long as there’s an easy meal — eggs, chicks, spilled feed, pet food, compost, fallen fruit — a property will keep drawing opossums no matter how many you remove.
Finally, the cleanup — flea-and-tick-laden bedding, droppings carrying leptospirosis and salmonella, and, in a barn, the EPM concern for horses — is work to do with protection and know-how, not a broom and a bag.
The BugBoss removal and exclusion process
We handle opossums as one complete job, in a deliberate order.
Inspect and assess. We confirm it’s an opossum, find the den and every access point under or into the structure, and — in spring and summer — determine whether a female is carrying or sheltering young, since that changes the timing and handling.
Remove humanely and legally. We remove the animal, and any dependent young, in line with Wisconsin’s nuisance-wildlife rules, handling disposition the way the state requires rather than the way that lands a homeowner in trouble.
Seal the den — dig-proof. We close the void with a buried, L-shaped barrier of heavy galvanized hardware cloth trenched down and bent outward around the deck, porch, shed, or slab skirt, and we screen or close the gaps into barns, crawl spaces, and outbuildings. Because opossums so often adopt an old skunk or woodchuck burrow, we backfill and block that ready-made den so it isn’t simply re-occupied.
Secure the food and the coop. On rural properties this is central: we advise on and, where it’s our work, help secure the chicken coop (tight at ground level and overhead), the feed and hay storage, and the garbage, compost, and pet-food draws that keep opossums coming.
Clean up. We remove den bedding and droppings, knock down the flea and tick load the opossum seeded into the yard and den, and address the contamination — with particular care in barns and feed areas on horse properties, given the EPM risk from droppings in feed and water.
This is core wildlife removal work for us, and because we’re full-service we can handle the fleas and ticks in the same visit and address any skunk or raccoon sharing the same ground-level real estate. For the broader approach to animals in and around a structure, our attic wildlife removal guide covers the exclusion philosophy that applies here too.
The reason we insist on all these steps comes down to how opossum problems recur. Remove the animal but leave the burrow open and scented, and the next drifter — or a skunk — moves into the furnished den. Seal the void but leave the coop and garbage open, and the property keeps drawing opossums to a now-closed den, so they find the next cavity. Do the removal and the seal but skip the flea-and-tick and droppings cleanup, and you’ve left a parasite reservoir and, in a barn, a horse-health hazard. An opossum job that actually holds is the one where the animal is out, the den and burrow are closed with buried steel, the coop and food are secured, and the parasites and droppings are cleaned up.
How do you keep opossums out?
Keeping opossums out is the same two-front job as the region’s other ground-denners: close the cavities and cut the food.
Structures and dens. Skirt every deck, porch, shed, and slab with a buried, dig-proof barrier, and close the gaps into barns, crawl spaces, and outbuildings. Backfill and block abandoned skunk and woodchuck burrows so an opossum can’t adopt one. Keep woodpiles, brush piles, and junk piles up off the ground and away from the house, since they make natural dens.
Food. Keep garbage in secured, latching cans, bring pet food indoors at night, manage compost so it isn’t an open buffet, and clean up spilled birdseed and fallen fruit. On rural properties, keep feed in metal containers, keep the feed room and hay storage closed up, and — the big one — secure the chicken coop tightly at ground level and overhead, because a coop is both a food source and a den in one.
None of this evicts an opossum already denning under a structure — exclusion and food control are post-removal and preventive measures, not a way to get a resident animal out. And the same buried-barrier work that opossum-proofs a deck also shuts out skunks and groundhogs, so the effort closes the whole ground-level wildlife problem at once. If bats are part of the same project, they’re protected in Wisconsin and can’t be excluded during the summer maternity season, so we sequence the work so nothing gets sealed at the wrong time.
When should you call BugBoss about opossums?
Call when you see the signs — an opossum coming and going from under a deck or shed, droppings and raided garbage or pet food, coop damage, or the animal itself moving through the yard at night. Call promptly if you keep it around a chicken coop or a horse barn, given the coop raiding and the EPM risk from droppings in feed and water. And while an opossum is a low rabies risk, still give distance to any animal that’s staggering, disoriented, or unnaturally tame, and let us handle it.
In the meantime, keep pets and children away from the den and from any droppings, don’t try to grab or corner the animal — the hiss-and-teeth display is bluff, but a bite is still a bite — and skip the mothballs and ammonia. If a female may have young in spring or summer, that’s all the more reason not to seal anything yet. The fastest path to a solved problem is an inspection that confirms what’s under the structure and whether there are young, followed by removal, a dig-proof seal, coop and food fixes, and cleanup in the right order.
Most pest-only companies serving this area won’t touch wildlife, and most trappers won’t do the exclusion, coop-securing, flea-and-tick knockdown, and cleanup that actually solve it. BugBoss does both, from our base right in Clintonville at 600 S. Main St., so you get humane removal, a dig-proof seal, food and coop fixes, and cleanup handled together by people you can reach directly. Call 866-BUGBOSS, or request a quote. No long-term contract, no cancellation fee, and you work with Brian, not a call center. We cover the full service area, from Clintonville and Marion to Waupaca, Shawano, and the surrounding rural towns and farms.