eavesdropping vs true bug

eavesdropping

noun
  • The act of one organism listening for another's calls, so as to exploit them. 

  • Listening secretly to the private conversations of others. 

  • The interception of electronic communication. 

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