bark louse noun2 •Any insect of the order Psocoptera, that live on or near trees and feed on algae and lichen.These include springtails (order Collembola), bark lice (order Ps[o]coptera),[…]. — 2002 •(no longer used) Any insect of the family Coccidae, that infest the bark of trees and vines.Housed plants are considerably injured by an oval bark-louse, the Coccus Hesperidum of Linnaeus, which has been introduced from abroad. — 1833 formsbark lice
