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 animals have significant defects in chemosensory responses. Mutant bristle organs exhibit morphological defects. In mutant socket cells, the apical membrane folds are dramatically disrupted and largely absent. In addition the shaft cell and neuron exhibit severe defects. The shaft cell fails to degenerate as normal after forming the bristle shaft. The cuticular shaft structures are normal. The neuron outer segment is also missing in mutants with only the crumpled remains of the dendritic sheath visible. Mutant larvae have a normal touch response.