Spanish fly vs turn-on

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. 

turn-on

noun
  • Something that attracts, gives pleasure, or encourages, especially sexually. 

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