Mutant adults exhibit behavioural defects: they have difficulty in walking, are unable to fly, have held-up wings, and are uncoordinated. Mutant animals have abnormal electrophysiological responses from mechanosensory bristles. Mutants exhibit a dramatic loss in mechanoreceptor potential (MRP). Transepithelial potential (TEP) is also severely reduced, even after voltage clamping of the bristle organ. Mutant larvae have a normal touch response.