vermin vs vexer

vermin

noun
  • Obnoxious, or mean and offensive person or people. 

  • Any one of various common types of small insects or animals which cause harm and annoyance. 

  • Animals that prey on game, such as foxes or weasels. 

vexer

noun
  • One who vexes; one who annoys 

How often have the words vermin and vexer occurred in a corpus of books? (source: Google Ngram Viewer )