A tegmen designates the modified leathery front wing on an insect particularly in the orders Dermaptera, Orthoptera, Mantodea, Phasmatodea and Blattodea. Wikipedia

In insects such as winged cockroaches and locusts, the tegmina are the stiff, membranous fore wings; in many species they are not primarily used for flight, but serve as protective covering for the delicate hind wings, which are the main organs of flight. Note that the more heavily armoured fore-wings of most beetles are called elytra, not tegmina. Wiktionary