This is a vast and heterogeneous family. Its default definition is based on external morphology criteria : the apex of the fastigium of the vertex has no furrow. The lower basal lobe of the hind femur is shorter than the upper one. The head is not conical. The median vein of the tegmina is almost always forked. Eades (2000) proposed to define Acrididae on the structure of male genitalia, especially the internal sclerites of the endophalle.