Is it ensure, insure, or assure?
Any of various insects of the order Plecoptera, having two pairs of large wings, long antennae, and chewing mouthparts. Plecopterans cannot fly well, and generally have dull coloring that allows them to blend in with their surroundings. Plecopteran nymphs can live up to four years before turning into adults. The stoneflies are plecopterans.