Crickets are Orthopteran insects which are related to bush crickets, and, more distantly, to grasshoppers. They have mainly cylindrically-shaped bodies, round heads, and long antennae. Behind the head is a smooth, robust pronotum. The abdomen ends in a pair of long cerci; females have a long, cylindrical ovipositor. Diagnostic features include legs with 3-segmented tarsi; as with many Orthoptera, the hind legs have enlarged femora, providing power for jumping. The front wings are adapted as tough, leathery elytra, and some crickets chirp by rubbing parts of these together. The hind wings are membranous and folded when not in use for flight; many species, however, are flightless. The largest members of the family are the bull crickets, Brachytrupes, which are up to 5 cm (2 in) long.