Together with type A GABA and strychnine-sensitive glycine receptors, glutamate-gated chloride channels (GluCl) are members of the Cys-loop family of ionotropic receptors, which mediate fast inhibitory neurotransmission. To date, GluCls are found in invertebrates only, and therefore represent potential specific targets for insecticides, such as ivermectin and fipronil. In this study, we identified the functional expression of GluCls in dorsal unpaired median (DUM) neurons of the metathoracic ganglion of Locusta migratoria using electrophysiological and molecular biological techniques. In whole-cell patch-clamped DUM neurons, glutamate-induced changes in both their membrane potentials (current-clamp) and currents (voltage-clamp) were dependent upon the chloride equilibrium potential. Upon continuous application of glutamate, the glutamate-elicited current response became rapidly and completely desensitized. Application of glutamate in the presence of 10 µM fipronil or 100 µM picrotoxin reversibly decreased GluCl-mediated currents by 87% and 39%, respectively. Furthermore, 1 µM ivermectin induced a persistent chloride current, suggesting the expression of ivermectin-sensitive GluCl subunits. A degenerate PCR/RACE strategy was used to clone the full-length Locusta migratoria LmGlCl subunit. Finally, RT-PCR experiments demonstrated the presence of LmGluCl transcripts in locust DUM neurons. Our results provide the first direct evidence of a functional ivermectin-sensitive GluCl channel on the cell surface of DUM neurons of L. migratoria.