Opossums are North America’s only native marsupials. An opossum vaguely resembles a cross between a housecat and a giant rat, and while they’re tolerated as a relative newcomer to Maine’s wilderness — migrating into the state within the last half century or so — they’re not especially cherished.
But perceptions of the creatures as being dirty or a threat to carry rabies are misguided, and more importantly, they may be your best defense against Lyme disease.
A study published by the American Journal of Public Health found that opossums, who are diligent self-cleaners with tough immune systems, are about eight times less likely to be carrying rabies than feral dogs.
And if you want to reduce the likelihood that you’ll be picking disease-carrying ticks off your body when you come in from an afternoon in the yard, you want as many of these ratlike creatures around your property as possible.
Rick Ostfeld, author of a book on Lyme disease and a senior scientist at the Cary Institute of Ecosystem Studies, described opossums as basically walking tick vacuums.
“Many ticks try to feed on opossums and few of them survive the experience,” Ostfeld said in a Cary Institute post. “Opossums are extraordinarily good groomers it turns out — we never would have thought that ahead of time — but they kill the vast majority, more than 95 percent percent, of the ticks that try to feed on them. So these opossums are walking around the forest floor, hoovering up ticks right and left, killing over 90 percent of these things, and so they are really protecting our health.”
Mainers don’t need to be reminded about the threat ticks represent. Eight-legged deer ticks are known to sometimes carry Lyme disease, the bacterial infection anaplasmosis, the parasitic infection babesiosis and the Powassan virus, all of which can be serious — and even fatal — under certain circumstances. By all accounts, tick populations are spreading and growing in Maine.
Opossums consider ticks to be tasty snacks, and easy ones at that. According to math extrapolated from the findings of a study published by the Proceedings of the Royal Society B., a single opossum can wipe out between 5,500 and 6,000 ticks per week.
“Although by most standards he is not a pretty fellow, our much-maligned marsupial, the Virginia opossum, should be viewed as the great ‘groundskeeper,'” reads a profile of the animal posted by the DFW [Dallas-Fort Worth] Wildlife Coalition. “Silently and without cost, he fulfills his role in the natural world, tending to it diligently and without fail. When left alone, the opossum does not attack pets or other wildlife; he does not chew your telephone or electric wires, spread disease, dig up your flower bulbs or turn over your trash cans. On the contrary, the opossum does a great service in insect, venomous snake, and rodent control.”
To be clear, having a few opossums around doesn’t absolve you from having to check for ticks when you come inside, nor from taking other anti-tick precautions, like wearing insect repellent or long sleeves.
But they certainly help your cause, and dramatically.
So how do you encourage the typically nomadic opossums to come around your property and clean up your ticks?
You can encourage opossums to frequent your lot by building opossum boxes — sort of like birdhouses, but for opossums. Here are instructions on how to do that: