Source : Webster's Revised Unabridged Dictionary (1913)

Lepidopterist \Lep`i*dop"ter*ist\, n. (Zo["o]l.)
   One who studies the Lepidoptera.

Source : WordNet®

lepidopterist
     n : an entomologist who specializes in the collection and study
         of butterflies and moths [syn: {butterfly collector}]