Detroit has a growing rat problem, according to a new study that found it among the worst in the country for rat infestation.

According to Orkin, Detroit ranks No. 7 in the list of Top 50 Rattiest Cities. That's up two spots from No. 9 last year.

The study comes out around this time every year as fall is the start of rodent season and as the weather gets colder, rats and mice seek out food, shelter and more to survive.

“Rats can squeeze through a hole the size of a quarter, while mice can fit through a hole the size of a dime,” John Kane, entomologist and technical director of Orkin’s ridwest region said. “Even if they can’t find an opening, they can often chew their way in.”

The Flint/Saginaw area came in at No. 49, down eight spots and Grand Rapids/Kalamazoo at No. 34, down one spot.

Chicago gained the top spot, followed by New York, Los Angeles, San Francisco/Oakland and Washington D.C.