chigger vs wheal-worm

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. 

wheal-worm

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