Larval behavioural phenotype: homozygous larvae have very low sensitivity to touch. Homozygous larval motility is visibly reduced. Adults can neither stand nor walk so die by adhesion. Gynandromorph mosaic individuals exhibit severe uncoordination of the legs. Gyandromorph mosaics were used for the bristle scratch test to test the mutant mechanosensory bristle function, the tegular and abdominal bristles fail to elicit the scratch response. Nervous system morphology is indistinguishable from wild type. The mechanoreceptor potential (MRP) is completely absent, even at a high transepithelial potential (TEP).