common green lacewing vs knapweed

common green lacewing

noun
  • a particular species of green insect in the order Neuroptera, Chrysoperla carnea 

  • a member of the genus Chrysoperla in general (the common green lacewing genus) 

knapweed

noun
  • Any of various common weeds of the genus Centaurea 

  • especially Centaurea nigra. 

How often have the words common green lacewing and knapweed occurred in a corpus of books? (source: Google Ngram Viewer )