chigoe vs harvest mite

chigoe

noun
  • A small tropical flea, Tunga penetrans, whose females burrow under the skin of animals, including humans, and lay their eggs, causing strong irritation and sores. 

harvest mite

noun
  • Any of various mites of the genus Trombicula that inhabit forests and grasslands and which, in their larval stage, attach to various animals including humans and feed on skin, often causing itching. 

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