Vermin is a word that is both plural and singular.

i.e. There was a vermin in my house.

i.e. Those rats are vermin.

Vermin is a noun.

Snakes are reptiles. They eat vermin.

No, raccoons are not vermin. They may be pests but such animals as rats and mice would be considered as vermin.

There is much debate regarding classifying badgers as vermin. Some argue they are vermin based on the definition of vermin as destructive creatures. Others say badgers are not destructive.