hornworm vs sphinx moth

hornworm

noun
  • Some moths in the genus Manduca of the hawk moth family Sphingidae. 

  • A caterpillar of a hawk moth that has a hornlike tail process. 

sphinx moth

noun
  • A moth of the family Sphingidae; a hawk moth. 

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