Responding to temperature to reach environmental conditions conducive to survival and prosperity is an important behavior in essentially all animals. Using the Drosophila larva as a model system, we connect the activity of cold sensing neurons to behavioral cold response. We identify neurons as specific cold sensors and find that their response to cooling as measured by in vivo calcium imaging is consistent with behavioral analysis of larval navigation on spatial temperature gradients. Laser ablation of the nerve connecting the proposed sensors to the central brain demonstrates that the neurons are required for cold avoidance. These results point toward a more complete neuronal circuit understanding of temperature sensorimotor transformation.