fall on vs infest

fall on

verb
  • To experience; to suffer; to fall upon. 

  • To be assigned to; to acquire a new responsibility, duty or burden. 

  • To occur on a particular day. 

  • Of the eyes or gaze: to alight upon. 

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 fall on and infest occurred in a corpus of books? (source: Google Ngram Viewer )