The mean free-running locomotor activity period of flies expressing cwodsRNA.IR.Scer\UAS under the control of Scer\GAL4tim.Scer\UAS is significantly longer than that of wild-type flies. Flies expressing cwodsRNA.IR.Scer\UAS under the control of either Scer\GAL4P2.4.Pdf or Scer\GAL41118 also show a long period phenotype. A large fraction of flies expressing cwodsRNA.IR.Scer\UAS under the control of either Scer\GAL4P2.4.Pdf are arrhythmic for locomotor activity under free-running conditions.