Blocking synaptic transmission in Tm5c neurons by expressing Ctet\TeTxLCTNT.13x.Ecol\lexAop.T:Ivir\HA1 under the control of Ecol\lexAC1a.DBD.ort.T:Zzzz\ZipRREEL and Hsim\VP16AD.VGlut.OK371.T:Zzzz\ZipEERRL,T:SV40\nls2 significantly reduces the phototactic preference for ultraviolet light over green light seen in wild type and control flies. No apparent defects in axonal or dendritic morphologies are seen.