gnat vs louse

gnat

noun
  • Any small insect of the order Diptera, specifically within the suborder Nematocera. 

  • An annoying person. 

louse

noun
  • A small parasitic wingless insect of the order Psocodea. 

verb
  • To remove lice from; to delouse. 

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