harvest mite vs hawthorn

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. 

hawthorn

noun
  • Any of various shrubs and small trees of the genus Crataegus having small, apple-like fruits and thorny branches 

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