labellum vs labium

labellum

noun
  • Part of the mouth of an insect, especially the sucking mouthparts of a fly. 

  • The lower central petal of a flower (especially an orchid), usually developed to be showy and attract pollinators. 

labium

noun
  • A lower mouthpart of an insect that is formed by the second pair of maxillae united in the middle line. 

  • The lip of a labiate corolla. 

  • A liplike structure; especially one of the two pairs of folds of skin on either side of the vulva. 

  • A liplike part of various invertebrates. 

  • The lip against which pressured air is driven to produce sound in a recorder and in a pipe organ with flue pipes. 

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