frequent vs infest

frequent

verb
  • To visit often. 

adj
  • Done or occurring often; common. 

  • Occurring at short intervals. 

  • Addicted to any course of conduct; inclined to indulge in any practice; habitual; persistent. 

infest

verb
  • To inhabit a place in unpleasantly large numbers; to plague, harass. 

  • To invade a host plant or animal. 

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