louse vs true bug

louse

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

verb
  • To remove lice from; to delouse. 

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 louse and true bug occurred in a corpus of books? (source: Google Ngram Viewer )