bedbug vs dragonfly

bedbug

noun
  • A small nocturnal insect (Cimex lectularius), of the family Cimicidae, that feeds on the blood of humans and other warm-blooded hosts. 

dragonfly

noun
  • An insect of the suborder Epiprocta or, more strictly, the infraorder Anisoptera, having four long transparent wings held perpendicular to a long body when perched. 

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