bugbear vs pester

bugbear

noun
  • A source of dread; resentment; or irritation. 

  • An ongoing problem; a recurring obstacle or adversity. 

verb
  • To alarm with idle phantoms. 

pester

noun
  • A bother or nuisance. 

verb
  • To bother, harass, or annoy persistently. 

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