Metro Detroit is one of the rattiest areas in America, according to a new report.

Orkin released their yearly ranking of the worst metro areas for rats. Orkin ranked metro regions by the number of new rodent treatments performed from September 15, 2017 – September 15, 2018.

For the fourth year in a row, Chicago takes the top spot, with Los Angeles, New York, Washington D.C. and San Francisco rounding out the top five.

Metro Detroit comes in at No. 6, which is one spot up from last year. The Grand Rapids-area comes in at No. 39 and the Flint-area comes in at No. 50.

During the colder months, rodent activity increases as these pests seek shelter in warm areas with readily-available food and water. In fact, the National Pest Management Association reports rodents enter an estimated 21 million homes in the U.S. each winter.

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“Rodents don’t need much of an invitation to enter your home,” said Chelle Hartzer, an Orkin entomologist. “A rat can squeeze through an opening as small as a quarter, while a mouse can wedge its way into a hole smaller than a dime.”

They chew through just about anything and can cause structural damage as they gnaw on electrical wires, gas lines and support beams. It’s estimated approximately 25 percent of unexplained fires start from rodent chewing.

“Aside from causing structural damage, rodents can carry hundreds of pathogens that can transmit various diseases and dangerous parasites. Additionally, they constantly leave behind droplets of urine as they travel each day. These droppings can contribute to asthma and allergic reactions, especially in children,” Hartzer added.

Here's the full list:

Chicago

Los Angeles (+1)

New York (-1)

Washington, DC (+1)

San Francisco (-1)

Detroit (+1)

Philadelphia (-1)

Cleveland, OH (+5)

Baltimore (-1)

Denver (+1)

Minneapolis-St. Paul (+1)

Dallas-Ft. Worth (-2)

Boston (+2)

Seattle (-5)

Atlanta (-1)

Indianapolis (+3)

Miami-Ft. Lauderdale (+1)

Hartford, CT (-2)

Pittsburgh (+3)

Cincinnati (+4)

Milwaukee

Charlotte, NC (+6)

Houston (-3)

Portland, OR (-7)

Columbus, OH (+6)

San Diego (+9)

Raleigh-Durham (+6)

Buffalo, NY (+2)

New Orleans (-6)

Norfolk, VA (-1)

Richmond, VA (-6)

Albany, NY (+4)

Kansas City, MO (-6)

Portland, ME (+19)

Nashville, TN (+5)

St. Louis, MO (-4)

Sacramento (-11)

Greenville, SC (+4)

Grand Rapids, MI (-5)

Phoenix (+4)

Orlando (+6)

Tampa (-4)

Burlington, NY (+11)

Champaign, IL (-3)

Rochester, NY (-6)

Syracuse (-1)

Charleston, WV (+17)

Dayton, OH (+7)

Memphis (-6)

Flint, MI (-1)