elytra and hidwings of a beetle

Elytra are the forewings of beetles (Order Coleoptera). They are hardened and heavily sclerotized and when the beetle is at rest the elytra close over the more delicate and membranous hindwings in order to protect them. During flight, the elytra are held open like a glider and the hidwings are used for propulsion. In some species the hindwings can be longer than the elytra but are folded underneath the elytra when at rest.