flea vs true bug

flea

noun
  • A small, wingless, parasitic insect of the order Siphonaptera, renowned for its bloodsucking habits and jumping abilities. 

  • A thing of no significance. 

verb
  • To remove fleas from (an animal). 

true bug

noun
  • Any of various insects of the order Hemiptera and in particular of the suborder Heteroptera, that are wingless or have two pairs of wings, and have mouthparts adapted for piercing and sucking. 

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