Fact Check

Are Opossums ‘Nature’s Pest Control’ and ‘Clean-up Crew'?

Unsung hero or overhyped nuisance? You decide.

Published Mar 23, 2022

A Didelphis Marsupialis opossum is pictured before being liberated at a reserve in Envigado, Antioquia department, Colombia, on January 29, 2022. (Photo by JOAQUIN SARMIENTO / AFP) (Photo by JOAQUIN SARMIENTO/AFP via Getty Images) (Getty Images)
Image Via Getty Images
Claim:
A viral meme claimed opossums are immune to rabies and ate up to 5,000 ticks annually, thus stopping the spread of Lyme disease.
What's True

It is true that opossums “eat insects, spiders, small rodents, and dead stuff.” However …

What's False

Opossums are not immune to either rabies or Lyme disease, though case incidents are rare. Furthermore …

What's Undetermined

While some evidence suggests opossums can eat 5,000 ticks per year, thereby reducing the spread of Lyme disease, research published in 2021 argued that such claims were extrapolated from limited data.

Curious about how Snopes' writers verify information and craft their stories for public consumption? We've collected some posts that help explain how we do what we do. Happy reading and let us know what else you might be interested in knowing.

Some say opossums are unsung heroes with a bad reputation. In recent years, social media users and news publications have presented research that supposedly claims the marsupials have innocuous bites for all of their notorious hype. (Not true, their bites are vicious.) Another claim readers sent us was the meme below, which called the white-faced, pointy-snouted animals “nature’s pest control and clean-up crew.”

To determine the accuracy of the above meme, we’ve fact-checked the four claims it presented. (And just so we’re all clear, yes, possum and opossum are the same animal.)

Claim: 'I’m Naturally Immune to Rabies.'

❌ Nope. Any mammal can get rabies, but some species are more prone to the viral disease than others. In the U.S., the Centers for Disease Control and Prevention reports that the most infected animals are raccoons, skunks, bats, and foxes.

Though it’s possible for an opossum to become infected with rabies, it is extremely rare. In fact, a 2013 study published in the Journal of the American Veterinary Medical Association found that of the documented cases of rabies across the country, there were just two infected opossums on record, making up 2.8% of the population.

“People often mistake the open mouth hissing and drooling behavior of opossums as a sign of rabies. However, this is just a bluffing behavior that opossums use as a defense mechanism,” writes the Humane Society.

“In fact, rabies is extremely rare in opossums, perhaps because they have a much lower body temperature compared to other warm-blooded animals.”

Claim: 'Just One of Me Eats up to 5,000 Ticks a Year.'

❓ Unproven. We’ve rated this claim as “unproven” because while it is true that opossums are good groomers and are known to eat ticks, it is not clear just how many bugs they are capable of eating in a season.

The 5,000 estimate was presented in a blog post published by the National Wildlife Federation that cited the Cary Institute of Ecosystem Studies, both of which are based on a 2009 study.

As writer Ken Perrotte described in an article published in Field and Stream, this claim is largely based on a study published in the biological research journal, Proceedings of the Royal Society B. Researchers in New York trapped six opossums in cages, inoculated each with 100 larval ticks, and left the parasites attached for four days (the agreed-upon time it takes a tick to feed). At the end of the study period, the researchers counted the ticks, either on the animal or on the floor of the cage, and assumed that those unaccounted for had been consumed by their host. From this limited dataset, they concluded that opossums, along with squirrels included in the study, killed between 83% and 96.5% of ticks, a number that was extrapolated to 5,000 ticks each season.

But that theory was tested in September 2021. Scientists publishing their work in the scientific journal Ticks and Tick-borne Diseases reviewed 23 papers that described opossums' eating behavior and analyzed the stomachs of 32 Virginia opossums (commonly known as the North American opossum) from Illinois and did not find evidence of ticks.

Why such a huge difference? Perotte gives two explanations. For one, it is possible that there may have been ticks left on the opossum even after four days, especially considering temperature can affect how the parasites feed. In short, the 2009 researchers assumed the ticks would feed and fall off, but they may have simply been still embedded on the animal.

“This body of memes turned out to be an extremely successful advocacy campaign for the opossum; allowing the oft-maligned scavenger to achieve cult status as a biocontrol for ticks,” concluded the 2021 study. “Unfortunately, these purported benefits are not supported by our findings or by previous diet analyses,” adding that it’s still possible to appreciate opossums, even if they’re not the little tick vacuums they were cracked up to be.

Claim: 'I Can’t Catch or Carry Lyme Disease.'

❌ Nope. Lyme disease is a bacterial infection spread by ticks and infects mammal populations around the world. When a tick bites an infected animal, the tick can become infected by the bacterium Borrelia burgdorferi and spread the bacterial infection to its next host, including opossums.

The Center for Food Security and Public Health at Iowa State University College of Veterinary Medicine notes that opossums can be infected with Lyme disease, however the Wildlife Habitat Council contends that it is a rare occurrence (though this could be for other reasons, like a lack of data on opossum populations). While it is true that opossums eat ticks, and thereby may inadvertently stop the spread of infected ticks, it’s not true that they can’t catch or carry Lyme disease.

Opossums are known carriers of fleas and ticks, both of which can infect household pets, and can carry diseases like leptospirosis, tuberculosis, relapsing fever, tularemia, spotted fever, toxoplasmosis, coccidiosis, trichomoniasis, and Chagas disease, according to University of California Agriculture and Natural Resources (UCIPM). The pest management program puts opossums on par with skunks and racoons, noting that once they have “invaded a neighborhood, they are probably there to stay so long as food, water, and shelter are available.”

Claim: 'I Also Eat Insects, Spiders, Small Rodents, and Dead Stuff!'

✅ True. Opossums are omnivores and have a taste for insects, snails, slugs, frogs, birds, and small mammals — but that’s not all. The Opossum Society notes that the marsupials love overripe fruit, and most gardeners can attest to their love of compost, pet food, and home-grown vegetables.

“Opossums that live near people may visit vegetable gardens, compost piles, garbage cans, or food dishes intended for dogs or cats. Having lost much of their natural fear of people, they will even enter a home through a pet door in search of food. Fortunately, they are not aggressive unless cornered, when they may hiss, growl, and show their teeth,” wrote UCIPM.

In short, yes, opossums may forage on critters that a person might not want in their garden. But their presence may cause more of an overall, long-term nuisance than a benefit.

“Opossums are considered a nuisance in gardens and near homes where they feed on berries, grapes, tree fruits and nuts, and defecate on garden paths and patios. They get into fights with dogs and cats and can inflict serious injury with their mouthful of sharp pointed teeth,” wrote UCIPM.

Unsung Hero or Overhyped Nuisance?

While it’s true that opossums eat ticks, thereby potentially preventing some spread of Lyme disease, their good characteristics may be overhyped by some social media users. Opossum-control mechanisms vary by state, but most pest control experts recommend treating their removal in the same way as one would treat raccoons or skunks. After determining that an opossum has moved in, experts say to make the surroundings less appealing to them by cleaning up overgrown shrubbery and trees that they may use to hide in, clean up fallen fruit, and hide garbage cans, pet food containers, or other food sources. Secure home areas so that they cannot hide out under stairways or other nooks and crannies.

Trapping or dispatching may also be appropriate options for those with opossum invaders. Learn more about how to deal with the animals here.

If you like reading about weird animal habits, you might also enjoy these stories from the Snopes critter country category:


Sources

In Defense of Opossums. https://www.wildlifehc.org/in-defense-of-opossums/. Accessed 23 Mar. 2022.

CDC. “Lyme Disease Home | CDC.” Centers for Disease Control and Prevention, 19 Jan. 2022, https://www.cdc.gov/lyme/index.html.

Dyer, Jessie L., et al. “Rabies Surveillance in the United States during 2013.” Journal of the American Veterinary Medical Association, vol. 245, no. 10, Nov. 2014, pp. 1111–23. PubMed Central, https://doi.org/10.2460/javma.245.10.1111.

Hennessy, Cecilia, and Kaitlyn Hild. “Are Virginia Opossums Really Ecological Traps for Ticks? Groundtruthing Laboratory Observations.” Ticks and Tick-Borne Diseases, vol. 12, no. 5, Sept. 2021, p. 101780. ScienceDirect, https://doi.org/10.1016/j.ttbdis.2021.101780.

Keesing, F., et al. “Hosts as Ecological Traps for the Vector of Lyme Disease.” Proceedings of the Royal Society B: Biological Sciences, vol. 276, no. 1675, Nov. 2009, pp. 3911–19. PubMed Central, https://doi.org/10.1098/rspb.2009.1159.

“New Study Says Possums Don’t Like Eating Ticks.” Field & Stream, 5 Jan. 2022, https://www.fieldandstream.com/conservation/possums-dont-eat-ticks/.

Opossum Management Guidelines--UC IPM. https://ipm.ucanr.edu/PMG/PESTNOTES/pn74123.html. Accessed 23 Mar. 2022.

https://ipm.ucanr.edu/PMG/PESTNOTES/pn74123.html. Accessed 23 Mar. 2022.

“Opossum,” O Lovely “Possum.” https://www.merriam-webster.com/words-at-play/possum-vs-opossum-difference-pronunciation. Accessed 23 Mar. 2022.

“Opossums: Unsung Heroes in the Fight Against Ticks and Lyme Disease • The National Wildlife Federation Blog.” The National Wildlife Federation Blog, 13 June 2017, https://blog.nwf.org/2017/06/opossums-unsung-heroes-in-the-fight-against-ticks-and-lyme-disease/.

Rabies | CDC. 22 Sept. 2021, https://www.cdc.gov/rabies/index.html.

“Why You Should Brake for Opossums.” Cary Institute of Ecosystem Studies, https://www.caryinstitute.org/news-insights/podcast/why-you-should-brake-opossums. Accessed 23 Mar. 2022.

Madison Dapcevich is a former writer for Snopes.

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