Larval behavioural phenotype: homozygous larvae have very low sensitivity to touch. Homozygous larval motility is visibly reduced. Less than 10% of adults are viable and the survivors exhibit severe uncoordination. Nervous system morphology is indistinguishable from wild type. 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. The mechanoreceptor potential (MRP) is completely absent, even at a high transepithelial potential (TEP).