Sentence:  When present the wings are membranous, with reduced venation, with the hind wing coupled to the larger fore wing in flight and at rest, when the wings are held roof-like over the abdomen (as shown here for the <WSD>bark louse</WSD> "Amphigerontia contaminata" (Psocidae); after Badonnel 1951). 
Meaning of the word marked with <WSD> tags:  Any insect of the order Psocoptera, that live on or near trees and feed on algae and lichen.