San Francisco, Oakland rank 4th on list of most rat-infested metro areas in the U.S.

SAN FRANCISCO (KGO) -- San Francisco and Oakland together rank as the fourth-most rat infested metro area in the country, according to a new report.

The cities ranked fifth on the list by Orkin Pest Control last year.

It's based on commercial and residential treatments from September of last year, to September of this year.

Chicago is number one. New York is number two and Los Angeles is third on the list.

Orkin says, around this time of year, rats and mice begin looking for warmer places to spend winter, and those places often end up being our homes and businesses.