Opossums are generally beneficial to have around your yard. They eat mice, rats, cockroaches, snails, slugs, and other common pests, and they carry an unusually low risk of rabies compared to other wild mammals. That said, they can cause property damage if they nest in your attic or crawlspace, and they pose a specific health risk to horses. Whether they’re “bad” depends on your situation.
Pest Control Benefits
Opossums are opportunistic omnivores that eat just about anything, and much of what they eat qualifies as a nuisance to homeowners. They kill and eat mice, rats, and cockroaches, along with snails, slugs, and other garden pests. They’re also partially resistant to snake venom, which means they can prey on venomous snakes that other animals avoid.
For years, opossums were celebrated as major tick killers based on a 2009 lab study that placed 100 larval ticks on captive opossums and found that roughly 96.5% of the ticks disappeared, presumably eaten during grooming. That study had only five opossums and was conducted in a confined setting. A more rigorous 2021 study reviewed 23 published papers examining opossum diets and gut contents and found no evidence that opossums eat ticks in the wild. Researchers also examined the gut contents of 32 opossum carcasses collected from Central Illinois and came up empty on ticks. So while opossums are genuinely useful pest controllers, the “tick vacuum” reputation is likely overstated.
Why Rabies Is Rarely a Concern
One of the biggest advantages of opossums over other backyard wildlife is their near-immunity to rabies. Their body temperature runs between 94 and 97°F, well below the 98.6°F typical of placental mammals like raccoons, skunks, and cats. The rabies virus needs temperatures above 98°F to replicate effectively, so it simply can’t survive inside most opossums. Their metabolic rate is only 30% to 50% as fast as a similarly sized mammal, which keeps their body temperature consistently low.
There have been a handful of recorded exceptions, likely in opossums running fevers at the time of exposure, but as a general rule opossums are among the least likely mammals to carry rabies. That doesn’t mean a bite is harmless. They can still carry other bacteria and pathogens, so any bite from a wild opossum warrants medical attention.
The Risk to Horses
If you keep horses, opossums become a more serious concern. They are the definitive host for a parasite called Sarcocystis neurona, which causes Equine Protozoal Myeloencephalitis (EPM). Horses get infected by eating feed or drinking water contaminated with opossum feces containing the parasite’s spore-like stages. In less than 1% of cases, these spores migrate from the horse’s intestinal tract into the bloodstream, cross the blood-brain barrier, and attack the central nervous system. There is currently no vaccine.
Prevention centers on keeping opossums away from horse feed and water. That means feeding horses in raised feeders rather than on the ground, maintaining clean and separate water sources, keeping feed rooms and containers sealed, cleaning up spilled grain promptly, and preventing wildlife access to areas where horses live. If you don’t have horses, EPM isn’t relevant to your household.
Property Damage From Nesting
Opossums become a nuisance when they move from passing through your yard to setting up residence. They commonly nest under decks, porches, sheds, and in crawlspaces or attics. Their strong claws let them climb siding, chimneys, trees, and soffits, and whatever they climb is at risk of being torn, punctured, or broken. Nesting opossums also produce foul smells that can linger on your property.
The damage is typically less severe than what raccoons or squirrels cause, but it adds up if left unaddressed. An opossum denning under your deck for a season will leave behind waste and potentially damage insulation or wiring in enclosed spaces.
Their Defensive Behavior
Opossums look intimidating when threatened. They’ll hiss, bare their teeth, and drool. But this is almost entirely bluff. When the display fails, their more famous defense kicks in: they enter an involuntary catatonic state, going limp and appearing dead. This “playing possum” response is not a conscious choice. It’s an automatic reaction, a temporary paralysis triggered by extreme stress. The opossum becomes unresponsive to external stimuli until the perceived threat passes.
This means opossums are among the least aggressive wild mammals you’ll encounter. They’re far more likely to freeze or collapse than to bite. That same instinct works against them on roads, where they sometimes go catatonic in response to oncoming cars instead of fleeing.
Keeping Opossums Out Without Harming Them
If you’d rather not have opossums on your property, the most effective approach is removing what attracts them. Focus on these common draws:
- Pet food left outside overnight
- Trash with loose lids or torn bags
- Open compost piles with food scraps
- Fallen fruit under trees
- Bird seed spilled or left out at night
A simple habit helps: do a quick check at dusk and bring in anything edible. If food isn’t available after dark, opossums typically move on within days.
Next, remove shelter options. Brush piles against fences, wood stacks sitting directly on the ground, sheds with gaps underneath, and low decks with open edges all look like safe dens to an opossum. Raise wood stacks off the ground, move brush piles away from structures, and trim vegetation back from decks and sheds.
To seal entry points under decks, porches, and sheds, use hardware cloth (sturdy metal mesh) rather than chicken wire. Attach it tightly along the full opening with no gaps, and bury the bottom edge 6 to 12 inches into the soil with the buried portion angled outward to prevent digging. One critical rule: never seal an area while an opossum is still inside. Confirm it has left before installing barriers.
Motion-activated lights and motion sprinklers placed along common travel paths (fence lines, deck edges, near trash cans) work well as deterrents. Run them nightly for one to two weeks while you’re removing food and shelter sources. Strong odors like garlic or ammonia-soaked rags placed outdoors can help short-term. Skip mothballs, which are toxic, and DIY essential oil sprays, which wash away after one rain.
The Bottom Line on Backyard Opossums
For most homeowners, an opossum passing through the yard is a net positive. It’s eating pests, it’s extremely unlikely to carry rabies, and it has no interest in confrontation. The calculus shifts if you have horses, if an opossum has nested inside a structure, or if you’re finding property damage. In those cases, humane exclusion and habitat modification solve the problem without needing to trap or relocate the animal.