Definition of oak eggar in US English:

oak eggar

(also oak eggar moth)

noun

  • A large brown Eurasian moth, Lasiocampa quercus (family Lasiocampidae), especially one of the subspecies L. quercus quercus, the larva of which feeds on a range of trees and shrubs (including oak).

Origin

Late 18th century; earliest use found in Moses Harris (1730–c1788), entomologist and artist.