varmint

noun2

1. •
   A pestilent or predatory ground-borne animal, especially one that kills or harasses a farmer's animals or crops.
2. •
   An obnoxious person or troublemaker.

   • You'd be but a fierce young hound indeed, if at your time of life you could help to hunt a wretched warmint, hunted as near death and dunghill as this poor wretched warmint is! — 1860