Generally, mantises protect themselves by camouflage and concealment. When directly threatened, many mantis species stand tall and spread their forelegs, with their wings fanning out wide. The fanning of the wings makes the mantis seem larger and more threatening, with some species having bright colors and patterns on their hind wings and inner surfaces of their front legs for this purpose. If harassment persists, a mantis may strike with its forelegs and attempt to pinch or bite. As part of the threat display, some species also may produce a hissing sound by expelling air from the abdominal spiracles. When flying at night, at least some mantises are able to detect the echolocation sounds produced by bats, and when the frequency begins to increase rapidly, indicating an approaching bat, they will stop flying horizontally and begin a descending spiral toward the safety of the ground, often preceded by an aerial loop or spin.