Do Opossums Eat Ticks? Where the 5,000-Tick Claim Came From

Do opossums eat ticks? The short answer

Wild opossums are not known to eat ticks in any real number. A 2021 study searched the stomachs of 32 wild Virginia opossums from central Illinois under a microscope and found no ticks or tick parts. The authors also reviewed 23 earlier diet studies, and none of them reported ticks either.

So why does everyone say they do? An opossum grooms itself often, and a 2009 lab study suggested it kills most of the young ticks that crawl onto it. That is a claim about ticks dying on an opossum’s body. It never showed that opossums hunt ticks or clear them from a yard.

Do possums eat ticks? That is the same question. In the US, “possum” is everyday shorthand for the Virginia opossum (Didelphis virginiana), the only marsupial native to the United States. It is a gray, pointy-nosed animal 24 to 34 inches (61 to 86 cm) long with its tail, and it weighs 4 to 15 pounds (2 to 7 kg).

Where the “5,000 ticks” figure came from

The number traces to one paper: Keesing and others, “Hosts as ecological traps for the vector of Lyme disease”, in Proceedings of the Royal Society B in August 2009. The team estimated that each opossum meets more than 5,500 tick larvae in a peak week and kills about 96.5% of them. Note the unit: a week, at the late-summer peak.

What the researchers actually did

In August and early September 2008, the team trapped six kinds of wild animals at the Cary Institute of Ecosystem Studies in Millbrook, New York. Opossums were one of them, with white-footed mice, chipmunks, gray squirrels and two songbirds. Each animal lived in a wire-floored cage over a pan of damp paper towels, so the team could count every tick that dropped off.

Next, they brushed 100 larval blacklegged ticks onto each animal’s head and neck. Larvae are the first stage, under 1 mm across. For four days the team counted the ticks that fell into the pans. On opossums, only 3.5% of the larvae fed and dropped off. On mice, almost half did.

The rest is the key point. A few ticks turned up unfed, but most of the ones placed on opossums never turned up at all. The paper says the missing ticks were “assumed to have been consumed or destroyed during grooming.” No one looked in the opossums’ stomachs or droppings for them.

How 199 ticks became 5,500

The big number is arithmetic, not a count. Wild opossums caught in New York at the larval peak carried about 199 fed larvae each. If those 199 are the 3.5% that survive, the team reasoned, each opossum must have met about 5,700 larvae that week. Take away the 199 that fed, and roughly 5,500 died.

Our reading: the study measured something real. Ticks do badly on opossums, far worse than on mice. What it did not measure is eating. In the retelling, “killed while grooming” turned into “eats”, and “a week at the peak” turned into a season or a year.

The retellings do not agree on the details

Even careful sources garble the study. The paper’s own table lists six opossums in the feeding test, yet Wildlife Illinois says four and Illinois Extension says five. Penn State Extension describes the estimate as per year, and Wildlife Illinois as per season. The paper itself says per week, during the larval peak.

What critics say the lab test missed

The 2021 authors raise three problems. First, opossums run cooler than mice and have lower blood pressure, and ticks feed more slowly on such hosts, so some larvae may still have been attached after four days. Second, the opossums went back to the woods without anyone combing their fur. Third, no one checked their stomachs or droppings, where tough tick parts would show.

The 2009 team saw some of this coming. They wrote that lab conditions could bias the results. They also held the animals four days because, in their data, few ticks stayed on any host longer than that. And ticks dropped off opossums no more often than off mice, which argues against ticks simply falling away.

What the 2021 opossum stomach study found

In 2021, Cecilia Hennessy and Kaitlyn Hild of Eureka College in Illinois searched the stomach contents of 32 wild Virginia opossums under a dissecting microscope. They did not sieve or rinse the contents first, so small parts could not wash away. They found no ticks and no tick parts, and they published the results in Ticks and Tick-borne Diseases.

The project began with a student question. Hild asked about the opossum tick meme in a wildlife class, Hennessy later wrote for the Illinois Department of Natural Resources. Road-killed opossums gave them only 11 animals in three seasons. After that, a licensed nuisance trapper supplied carcasses of animals he had euthanized.

The stomachs held the usual opossum mix. Hennessy lists worms, a French fry, broken glass and a mostly undigested shrew. There were also three whole fleas, a hint that opossums do swallow some pests while grooming. Yet not one tick turned up, even though ticks were on the opossums’ bodies, Illinois Extension notes.

Over 1,280 opossums: is that number real?

Yes, with one caveat. Google’s AI answer says studies of over 1,280 wild opossums found no ticks. The figure comes from Hennessy’s 2023 article: across 23 published diet studies, starting with John James Audubon in 1851, she counted results for over 1,280 opossums. None reported ticks anywhere in the gut. The caveat: 4 of the 23 studies looked at droppings, not stomachs.

What the stomach study cannot prove

No single study settles it, and this one has limits too. A stomach holds only the last few hours of meals, and 32 animals from one part of Illinois is a small sample. Readers on Reddit raise a fair point as well: a tick larva is tiny, so could it digest before anyone sees it? Hennessy’s answer is that tick parts are tough and stay recognizable even after passing through the gut.

So, do opossums eat ticks after all? Weighed together, the evidence says they may kill some ticks that try to bite them. But ticks are not a food they seek out, and no study has found them in an opossum’s diet. Penn State Extension adds a simple test. Opossums are common across the deer tick’s range, often in suburbs. If they trapped ticks by the thousand, it argues, tick numbers and Lyme disease there would show an obvious drop.

How the opossum tick myth spread: a timeline

The claim took about 8 years to go viral and 12 years to get tested. It started as one line of arithmetic in a 2009 paper, grew into “unsung heroes” in the press by 2015, and became “5,000 ticks a season” on blogs and memes by 2017. Do opossums eat ticks in the wild? Nobody looked inside one to check until 2021.

Two things helped it spread. The estimate came from a respected lab, so each retelling felt safe to repeat. And the story was kind to an animal many people dislike. Hennessy points out the cost: people began putting out food to draw opossums in. That food also draws raccoons, rats, stray cats and coyotes.

What do opossums eat?

Opossums eat almost anything, but they prefer animal food. The Missouri Department of Conservation lists insects, carrion, mice, reptiles, frogs, crayfish, birds and their eggs, and earthworms. In fall and early winter they add fruit such as persimmons, grapes and pawpaws. Near homes, they raid open trash cans and pet food left outdoors.

Opossums do earn their keep in other ways. Missouri’s field guide notes that they eat many insects farmers count as pests and clean up carrion. Foxes, coyotes, bobcats and owls hunt them in turn. When cornered, an opossum shows its teeth and drools first, then plays dead: it goes limp, shuts its eyes and lets its tongue hang out.

Do opossums carry ticks and Lyme disease?

Yes, opossums carry ticks, often many of them. In the 2009 New York study, wild opossums held about 199 fed larvae each in a peak week. Yet they are poor carriers of the Lyme bacterium. The same paper found that opossums infected only about 3% of the ticks that fed on them, against about 92% for white-footed mice.

That makes the opossum a mixed case. Some ticks finish feeding on it, drop off wherever it wanders, and molt into nymphs, including in your yard. However, those ticks rarely leave an opossum carrying Lyme bacteria. CDC says young ticks usually pick up the bacteria from a rodent, which is why mice matter more than opossums for Lyme risk.

You cannot catch Lyme disease by touching an opossum. CDC says the bacteria reach people through the bites of infected blacklegged ticks. Our deer tick guide covers that tick, its size at each stage and where it lives.

Can opossums get rabies?

Yes, but it is rare. In CDC’s national count for 2013, only 2 of the 5,865 rabid animals reported in the US were opossums, against 1,898 raccoons. So the popular line that opossums are “immune” to rabies is wrong. They simply get it far less often than raccoons, skunks, foxes and bats.

Low odds are not zero, though. If any wild mammal bites or scratches you, call your doctor or local health department the same day. They decide whether you need rabies shots, and that holds for an opossum too.

A risk for horses

Horse owners have one more reason to keep opossums away from feed. Opossum droppings spread Sarcocystis neurona, the parasite behind equine protozoal myeloencephalitis (EPM), a nerve disease of horses. The Merck Veterinary Manual advises keeping feed in closed metal bins, removing fallen fruit and keeping opossums out of feeding areas.

Should you want opossums in your yard?

Leave them be, but do not invite them. An opossum passing through is harmless and does real cleanup work, yet it will not lower your tick numbers. Food or shelter set out for opossums also draws raccoons, rats, stray cats and coyotes, warn Illinois Extension and Wildlife Illinois. It teaches wild animals to link people with food, too.

Do possums keep ticks away, then? No. An opossum that visits every night may even bring a few ticks in on its fur. If ticks are a problem in your yard, the woods edge and the stone walls are where to look, not the wildlife passing through.

Forums show how the myth turns into action. One Reddit post praises an opossum that eats leftover kibble on the porch and “in return keeps my backyard tick-free.” In another, a reader wanted to pull ticks off a wild opossum. Both are kind ideas, and both bring people and wildlife closer than is safe.

What actually lowers ticks around your home

No animal clears ticks from a yard. Penn State Extension concludes that chickens and guinea fowl eat some ticks but not enough, and that opossums probably eat none. What works is yard work at the woods edge, tick tubes or bait boxes where mice are common, and, last, a registered tick spray. On your own body, repellent and a tick check do the rest.

For the yard, our guide to getting rid of ticks in the yard and house covers the edge work, tick tubes and how to read a spray label. For your body, the tick bite prevention guide compares repellents and explains permethrin clothing. If you want to know which animals do take some ticks, see what eats ticks.

Found one already attached? Our guide to removing a tick with tweezers walks through it, including what to do if the mouthparts stay in. For everything else about ticks, start at our tick hub.

Opossum and tick myths, corrected

Search “do opossums eat ticks” and six claims come up again and again on the pages that rank. Each one below sits next to what the research says. Most of them trace back to the same 2009 estimate, retold with the details dropped.

• Myth 1

  Myth: “An opossum eats 5,000 ticks a season.”

  Truth: The only estimate, from 2009, was about 5,500 larvae a week at the late-summer peak. It counted ticks that went missing from six caged opossums, not ticks found in a stomach (Keesing and others, 2009).

• Myth 2

  Myth: “Opossums hunt ticks in your yard.”

  Truth: Even the 2009 study only proposed that opossums groom off ticks that climb onto them. They forage for insects, carrion and fruit (Missouri Department of Conservation).

• Myth 3

  Myth: “Opossums do not carry ticks.”

  Truth: Wild opossums in New York carried about 199 fed larvae each in a peak week (Keesing and others, 2009).

• Myth 4

  Myth: “Opossums cannot get rabies.”

  Truth: They can, but it is rare: 2 of 5,865 rabid animals in the US in 2013 (CDC, Dyer and others, 2014). See a doctor the same day after any bite or scratch from a wild animal.

• Myth 5

  Myth: “Feeding opossums helps control ticks.”

  Truth: It draws raccoons, rats and cats as well, and it will not cut ticks (Illinois Extension; Illinois DNR). Leave wild opossums to find their own food.

• Myth 6

  Myth: “Opossums spread Lyme disease to people.”

  Truth: Lyme reaches people through tick bites, and opossums infect only about 3% of the ticks that feed on them (CDC; Keesing and others, 2009).

Pest control disclaimer. Photo-based identification can help, but it is not always perfect. For dangerous spiders, large infestations, or anything you are unsure about, contact a licensed pest control professional.