Ninety-four putative G protein-coupled receptors (GPCRs) were identified in the Musca domestica genome. They were annotated and compared with their homologs in Drosophila melanogaster. Phylogenetic analyses of the GPCRs from both species revealed that several family members shared a closer relationship based on the domain architecture. The expression profiles of these genes were examined by quantitative RT-PCR among three strains of the house fly, a near isogenic line (N-IRS) strain with imidacloprid-resistance, the corresponding susceptible strain (CSS), and another strain derived from field populations with imidacloprid resistance (IRS). We found that five GPCR genes were up-regulated in the N-IRS and eight GPCR genes up-regulated in IRS strains compared to the CSS strain. The transgenic lines of Drosophila melanogaster with the GPCR genes (LOC101899380 in the N-IRS strain and LOC101895664 in the IRS strain) exhibited significantly increased tolerance to imidacloprid, and higher expression of P450 genes. Bioinformatic analysis of LOC101899380 was carried out based on its full-length nucleic acid sequence and putative amino acid sequence, named Mth-like10 due to its homology with Drosophila Mthl10. A cell-base Cell Counting Kit-8 (CCK-8) toxicity assay demonstrated that the expression of the GPCR gene (LOC101899380) in Spodoptera frugiperda (Sf9) cells using a baculovirus-mediated expression system can elevate the cell tolerance to imidacloprid, indirectly supporting the hypothesis that the GPCR gene (LOC101899380) plays some role in imidacloprid resistance. These results should be useful for furthering understand of the regulatory pathway by which house flies develop resistance. This article is protected by copyright. All rights reserved.