Sensory neuron membrane proteins (SNMPs) in insects are critical peripheral olfactory proteins and act as markers for pheromone detection. However, the SNMPs for onion maggot, Delia antiqua Meigen, a world-wide subterranean pest, have not been previously characterized. In this study, we first report the cloning and characterization of two novel SNMPs from D. antiqua, DantSNMP1 and DantSNMP2. Sequence alignment and phylogenetic analysis showed that DantSNMP1 and DantSNMP2 are very similar to the previously reported SNMP1 and SNMP2 isolated from other dipteran insects but they share low identity with each other. Further expression profile experiments showed that DantSNMP1 is antenna-specific, while DantSNMP2 is expressed both in antennae and nonantennal tissues. Immunocytochemical localization experiments showed that DantSNMP1 was expressed only in sensilla trichodae, which suggests that this protein is involved in pheromone reception in insect olfaction.