Moreton Bay bug vs crawfish

Moreton Bay bug

noun
  • The species Thenus orientalis of the slipper lobster family; a common seafood item. 

crawfish

noun
  • Various marine crustaceans, rock lobster; especially Jasus lalandii, the Cape crawfish. 

  • Various freshwater crustaceans, crayfish. 

  • A slur against Anglo-Canadians used in some corners of Quebec (including the Gaspé). 

verb
  • To backpedal, desert or withdraw (also used with out). 

How often have the words Moreton Bay bug and crawfish occurred in a corpus of books? (source: Google Ngram Viewer )