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Rats And Mice Are Headed Indoors For The Winter. Here’s How To Keep Them Out

A mouse can get into your home by fitting in an opening the size of a pen; for rats, a dime-size hole will do, a pest expert said. “It’s a serious health hazard; and once they’re inside, the damage is done."

A rat scampers through the West Loop area on Feb. 26, 2021.
Colin Boyle/Block Club Chicago
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CHICAGO — Rats and mice are getting ready to sneak into homes so they can stay warm during Chicago’s long winter.

It’s just part of the seasonal change in Chicago, which on Thursday was dubbed the “rattiest city” in the United States for the seventh year in a row by Orkin, a pest control company.

The good news: It’s possible to reduce the chance of critters, including squirrels and chipmunks, making themselves comfy in your home.

Janelle Iaccino, marketing director of Rose Pest Control, said residents should thoroughly check building perimeters and basements. 

“Keep the leaves away from the foundations. Keep your bushes trimmed,” Iaccino said. “In urban settings, make sure to dispose of garbage properly and not to keep it on the balcony, because rodents can easily climb, especially on bricks.”

It’s also important to keep backyard gardens tidy, Iaccino said.

“Don’t leave pots and plants around, and keep your patio space clean,” she said.

Indoors, the only way to keep rodents out is to spot every possible point of access, said Rebecca Fyffe, director of research at Landmark Pest Management.

“For mice, this is anything you can get a pen into, while for rats, a dime-size hole is enough,” she said. 

Many people try to close openings with expanding spray foam, but rodents seem to enjoy eating through it, experts said. Steel wool is another common material that needs to be avoided; it’s affected by moisture and rusts over time, making it easy for rodents to dislodge. 

The only way to block access points is to use specific products, such as metal angle irons.

“The brand that I recommend the most is called Xcluder,” Fyffe said. “It looks similar to steel wool, but it’s stainless, and it has an extra layer of melted plastic.” 

It’s a hard material that is painful for rodents to chew. It doesn’t rust, and it stays in place over time, Fyffe said. 

If rodents are already present in a home, the homeowner’s job is much tougher, experts said. In those instances, residents can use a combination of traps and rodenticide, Fyffe said.

“Rodenticide is not inherently bad, but it’s definitely overly relied on,” Fyffe said. “It’s only appropriate indoors as a knockdown agent and in areas not accessible to dogs. But outdoors it’s dangerous, as it can go up the food chain, and it’s not sustainable.” 

Iaccino said the best option is to call an exterminator once rats and mice are indoors. 

“It’s a serious health hazard, and once they’re inside, the damage is done,” she said. “Remember that if you see one rodent, there’s at least a family of six through 12 hidden somewhere.”

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