They usually have thin legs that are held folded at right angles to the body, sometimes close to the horizontal plane.

They have three segmented tarsi and have a short antenna with a knobby organ at the tip.

They are considered primitive within the Orthoptera and feed on algae, ferns and gymnosperms, the more ancient plant groups.

With the exception of the central Asian Gomphomastacinae, all other subfamilies are restricted to South America.

This article about a member of the insect family Eumastacidae is a stub.