chigger vs sand flea

chigger

noun
  • A chigoe (Tunga penetrans), a kind of flea found in tropical climates. 

  • A harvest mite, a very small, red mite endemic to the Midwestern and Southeastern US, the infestation of which causes intense itching. 

  • An East Asian person who behaves in ways similar to a stereotypical urban African American. 

sand flea

noun
  • A small tropical flea, Tunga penetrans; a chigoe (family: Tungidae, order: Siphonaptera). 

  • Any of various small crustaceans of the family Talitridae (order Amphipoda), that are found on beaches and jump like a flea. 

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