June beetle vs June bug

June beetle

noun
  • Any of several scarab beetles that appear around June in temperate parts of North America. 

June bug

noun
  • green June beetle (Cotinis nitida), of the southeastern United States 

  • European chafer (Rhizotrogus majalis/Amphimallon majalis), a beetle native to continental Europe, but now also in North America 

  • ten-lined June beetle (Polyphylla decemlineata), of the western United States and Canada 

  • Phyllophaga, a genus of beetles in the subfamily Melolonthinae of the family Scarabaeidae, also known as June beetles. 

  • fig-eater or figeater beetle (Cotinis mutabilis), of the western and southwestern United States 

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