ladybug vs praying mantis

ladybug

noun
  • Synonym of ladybird. 

praying mantis

noun
  • A woman who preys on men (from the idea that female praying mantises eat males after sex). 

  • Any of various predatory, cannibalistic insects of the order Mantodea that have a prayer-like stance. 

  • A mantid of the species Mantis religiosa. 

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