Odorant binding proteins (OBPs) contribute to the remarkable sensitivity of the insect's olfactory system and play important roles in the olfactory recognition. The orange blossom midge, Sitodiplosis mosellana is a cereal specialist, and utilizes pheromone and host odorant as a cue for its mating and oviposition. However, OBP genes have not been largely identified in S. mosellana. Based on the sequenced transcriptome database, twenty-six OBP genes were identified in S. mosellana for the first time. Phylogenetic analysis revealed that S. mosellana OBP genes are more closely related to Mayetiola destructor OBP genes than to Aedes aegypti OBP genes. Most OBP genes seemed to be antenna-specific, but differentially expressed in male and female antennae. Three OBP genes (OBP9, OBP19 and 0BP23) are leg-specific. And also, most OBP genes have higher expression levels in adults. Only one OBP gene (OBP10) has higher expression levels in larval stages. These findings serve as an important basis for understanding the molecular mechanisms of chemosensory perception. (C) 2014 Elsevier Inc. All rights reserved.