Insects detect volatile chemicals using antennae, which house a vast variety of olfactory sensory neurons (OSNs) that innervate hair-like structures called sensilla, where odor detection takes place. In addition to OSNs, the antenna also hosts various auxiliary cells. These include the triad of trichogen, tormogen and thecogen support cells that lie adjacent to their respective OSNs. The arrangement of OSN supporting cells occurs stereotypically for all sensilla and is widely conserved in evolution. While insect chemosensory neurons have received considerable attention, little is known about the functional significance of the cells that support them. For instance, it remains unknown whether support cells play an active role in odor detection, or only passively contribute to homeostasis, e.g. by maintaining lymph composition. To investigate the functional interaction between OSNs and support cells, we used optical and electrophysiological approaches in Drosophila. First, we characterized the distribution of various auxiliary cells using genetic markers. By means of an ex vivo antennal preparation and genetically-encoded cation indicators, we then studied the activation of these auxiliary cells during odor presentation. We observed acute responses and distinct differences in Ca²⁺ and K⁺ fluxes between support cell types. Finally, we observed alterations in OSN responses upon thecogen cell ablation. These changes occur in a sensillum-specific fashion, without changes in neuronal resting activity. For example, ab1 OSNs show increased responses, while ab3 OSNs show decreased responses in the absence of thecogen cells. Taken together, these results demonstrate that support cells play an active role in odor processing. Our observations thus suggest that support cells functionally interact with OSNs and may be important for the extraordinary ability of insect olfactory systems to dynamically discriminate between odors in the turbulent sensory landscape of insect flight.