The summer of 1985 I worked in downtown Buffalo right on the river next to the General Mills plant where they make Cheerios. Every time they burned/overcooked a batch of Cheerios they came out a conveyor belt to a big pile outside the plant. At night the rats came out. Biggest Cheerios fed rats I have ever seen.
Yuck!
My husband knew someone who worked in a bread factory. At night some employees would come into the factory with guns for target practice on the rats.