Odor controls were performed exactly as the test described above, except that instead of choosing between two different odors, flies chose between each single odor and air streamed through mineral oil. Preference index was calculated by (# flies in odor vial - # flies in air vial) / total # flies. Odor control data for all UAS-GAL4 experiments is presented in Supplementary Table 1 and for all sca-related experiments is presented in Supplementary Table 5.
