dragonfly vs insect

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. 

insect

noun
  • An arthropod (in the Insecta class) characterized by six legs, up to four wings, and a chitinous exoskeleton. 

  • A contemptible or powerless person. 

  • Any small arthropod similar to an insect, including spiders, centipedes, millipedes, etc. 

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