Oocyte and larval physiology were performed largely as described15 (link),28 (link), with additional details provided in Methods. Chemical sensitivities of wild type and mutant (dTRPA1-2C) channels were assessed by normalizing all currents to currents observed at 1mM AITC. Chemically unrelated insect repellents like DEET, IR-3535, and deltamethrin failed to activate dTRPA1 (K.K. and P.G., unpublished).