Some combinations of cpo mutants show bang sensitive paralysis. The paralytic phenotype following mechanical stimulation show incomplete penetrance. Paralysis usually lasts approximately 25-45 seconds, during which time flies lie completely motionless with occasional slight leg movement. The mutants do not display hyperactivity as they recover, but instead just right themselves to a standing position and resume normal behaviour. Upon recovery, the flies do not show a well-defined refractory period. Following bang sensitive paralysis, mutants do not always become reparalysed, even when tested a day later, probably owing to the incomplete penetrance of the bang sensitive phenotype.