A family selection scheme, based on the progeny from individual females, was used to select several families of the insect vector Culicoides variipennis that were resistant or susceptible to oral infection with bluetongue virus. Genetic crosses between families showed results consistent with control by a single genetic locus (blu). Reciprocal crosses suggested a maternal effect in which the genotype of the mother determined the phenotype of the offspring. The dominant and recessive natures of the resistant (blu(r)) and susceptible (blu(s)) alleles were determined by the sex of the parent. The results provide the first evidence to suggest a genetic locus controlling insect vector competence for infection with an arbovirus.