A psocopteran, Pseudicaecilius sp., showing features typical of Psocotera, commonly known as booklice, (a, c) or Paraneoptera (b). (a) Wing-folding mechanism; (b) wing coupling mechanism; (c) Pearman’s organ. Body length 1.3mm.
Evolution of the Insects. By David Grimaldi and Michael S. Engel
Cambridge Unversity Press. NY, USA 2005