European chafer vs green June beetle

European chafer

noun
  • A beetle, Amphimallon majale, native to continental Europe, now an invasive species in North America. 

green June beetle

noun
  • Cotinis nitida, a species of beetle found in the eastern United States and Canada. 

How often have the words European chafer and green June beetle occurred in a corpus of books? (source: Google Ngram Viewer )