insect vs mollusc

insect

noun
  • A contemptible or powerless person. 

  • An arthropod (in the Insecta class) characterized by six legs, up to four wings, and a chitinous exoskeleton. 

  • Any small arthropod similar to an insect, including spiders, centipedes, millipedes, etc. 

mollusc

noun
  • A weak-willed person. 

  • A soft-bodied invertebrate of the phylum Mollusca, typically with a hard shell of one or more pieces. 

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