arachnid vs hemipter

arachnid

noun
  • Any of the eight-legged creatures, including spiders, mites, and scorpions, of the class Arachnida. 

hemipter

noun
  • Any organism of the order Hemiptera, including cicadas, aphids, planthoppers, leafhoppers, and shield bugs. 

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