Reporter activity is detected in the C1 chordotonal organ precursor cells of each thoracic and abdominal body segment with higher levels in the oenocyte-producing abdominal segments at embryonic stage 11. In older embryos, it is present in this lineage in abdominal but not thoracic segments. ato and sens are detected in sensory precursor cells in embryonic, stage 9, earlier than the rho reporter. All three are co-expressed in C1 SOP cells of slightly older embryos (stage 11).