As human beings around the world change their daily behavior to try to slow the spread of the novel coronavirus, our absence is causing ripple effects in the urban ecosystem. Among the most noticeable changes: Rats are coming out of hiding. They’re taking to the streets in broad daylight and invading homes in a desperate search for food.

In New Orleans’s storied French Quarter, the tourists—and their trash—are gone. Suddenly hungry rats are venturing forth during the day in large numbers. In Seattle, rats have been seen wrestling in public parks in the afternoon. “They did not scurry or dart or dash,” writes The Stranger’s Charles Mudede. “They instead pranced about the wood chips like students in a high school musical.”

People who have never have rat problems before are suddenly coping with unwanted visitors invading their social isolation. Annette and Andreas Spreer have stored root vegetables, cabbages, and apples in their cellar on and off since 1995. They live in Stuttgart, Germany, where restaurants have been closed since March 22, and people are staying home as much as they can. A few days ago, for the very first time, she noticed some of her potatoes looked as if they had been gnawed on. “They didn’t eat the apple or the cabbage or carrots. Just the potatoes.” Annette says. “I could not believe this could happen.”

Stories like these are likely playing out around the world, according to Robert Corrigan, famed urban rodentologist, who lends his expertise to cities across the globe as an independent consultant. He says that as particular colonies of rats lose their established food sources—whether it’s litter and trash cans in parks, or dumpsters outside restaurants—they will start fighting over any food that’s left. Some rats will kill and eat their own kind to survive. (Corrigan says the Seattle park rats were likely “duking it out for the kill.”) Others will strike out into the unknown, looking for new food sources.

View Images Rats raid a trash can in lower Manhattan before the coronavirus pandemic. Normally New Yorkers with uptown and downtown addresses dump enough trash on the streets for rats to be able to live out their lives less than 150 feet from where they were born, but now its likely more will be entering homes to find their next meal. Photograph by Charlie Hamilton James, Nat Geo Image Collection

Home for dinner

If hungry rats smell food in your house, there’s a good chance they’ll try to come in. “They are going to follow their nose below that door if they can,” Corrigan says. (Read about how rats became an inescapable part of urban living.)

Once inside, rats will be as bold as they need to be to find food to survive. “It is a wild animal. It is going to go forage around the house,” Corrigan says. “If there is a baby in a crib with a milk bottle, they are going to follow that odor. They can chew on wires; they can bring their own viruses in. Rats in the house is serious.”

Rats themselves can carry disease. There’s no evidence that they can become infected with SARS-CoV-2, the virus that causes COVID-19. But Corrigan worries they could move the virus around by slithering through sewer pipes full of feces and then sauntering through people’s homes. “If we can transmit it on our fingertips, then of course rats can transmit it on their feet, their fur, their tails,” Corrigan says.

Even if sewer rats bring human feces into your home, though, you shouldn’t panic. While virus has been found in the feces of infected hospital patients, the Centers for Disease Control and Prevention says that the risk of transmission from feces is thought to be low.

Home hygiene

In any case, now might be a good time to improve your home hygiene, just as many of us have stepped up our hand-washing. Outdoor trash containers should have secure, tight-fitting lids. Cracks under doors and other openings to the outside should be sealed. Rats can squeeze under a door that’s just a half-inch off the floor, and mice can wriggle under a crack a quarter-inch tall, Corrigan says.

If rats or mice do make it into your house, the good news is that pest control is considered an “essential service” and is open for business, according to Jim Fredericks, chief entomologist for the National Pest Management Association. “People think of pest control as a luxury or pests being just a nuisance, but there are many pests that are a threat to public health, to our food supply, [and] to our properties,” Fredericks says.

View Images Rats emerge from a gap in the sidewalk on Pearl Street, in New York City.

Photograph by Charlie Hamilton James, Nat Geo Image Collection

The risk from rodents is significant enough, he says, that it’s worth allowing a pest control specialist into your home if necessary. When you call to book an appointment, Fredericks recommends asking the company what steps it will take to minimize the risk of coronavirus coming in with the technician. “Pest control companies have been adapting to this new normal,” Fredericks says. “We’ve had reports from members in which they are providing additional training in maintaining safe distances, sanitizing, washing hands.”

Fredericks adds that if rodents are hungry enough to move into new places to search for food, they are also likely hungry enough to take bait from traps. (Keep in mind some methods of killing rats cause more suffering than others: Poison and glue traps kill slowly and painfully, while good snap traps kill instantly. There’s also the option of live traps, followed by release in a field or the woods.)

Different rats occupy different ecological niches in the city. Park rats are likely to be particularly hard hit, as trash bins sit empty and picnics cease. These rats, forced to forage out in the open, may become easy prey for urban hawks, owls, coyotes, and raccoons.