Spanish fly vs erotic

Spanish fly

noun
  • A supposed aphrodisiac extracted from the beetle Lytta vesicatoria; cantharidin, the active ingredient, a vesicant used as a defence by L. vesicatoria and other blister beetles. 

  • The beetle Lytta vesicatoria. 

erotic

adj
  • Relating to or tending to arouse sexual desire or excitement. 

noun
  • An amorous composition or poem. 

How often have the words Spanish fly and erotic occurred in a corpus of books? (source: Google Ngram Viewer )