dung beetle vs sacred beetle

dung beetle

noun
  • Any of the true dung beetles of subfamily Scarabaeinae. 

  • Any of the beetle of the family Scarabaeidae (scarab beetles), especially of the subfamilies Scarabaeinae and Aphodiinae, noted for rolling dung into balls for use as food or as brooding chambers. 

sacred beetle

noun
  • The Egyptian scarab. 

How often have the words dung beetle and sacred beetle occurred in a corpus of books? (source: Google Ngram Viewer )