potato beetle vs potato bug

potato beetle

noun
  • the Colorado beetle, Leptinotarsa decimlineata 

potato bug

noun
  • The Colorado beetle or Colorado potato bug (Leptinotarsa decemlineata). 

  • Any of various insects that feed on or harm potato plants. 

  • The Jerusalem cricket, various insects of the genus Stenopelmatus. 

  • The striped blister beetle or old-fashioned potato bug (Epicauta vittata). 

  • The woodlouse, various terrestrial crustaceans of suborder Oniscidea. 

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