Easton's Bible Dictionary: M. G. Easton, M.A., D.D.
Heb.'ash, from a root meaning "to fall away," as moth-eaten garments fall to pieces (Job 4:19, 13:28; Isa. 50:9, 51:8; Hos. 5:12).
Gr.ses, thus rendered in Mt. 6:19, 20; Lk. 12:33. Allusion is thus made to the destruction of clothing by the larvae of the clothes-moth. This is the only lepidopterous insect referred to in Scripture.