dragonfly vs ladybug

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. 

ladybug

noun
  • Synonym of ladybird. 

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