Sweat bees [Lasioglossum (Dialictus) figueresi] returning to their nests were not disturbed if small-scale landmarks were added near nests before bees made orientation flights. Landmarks added after orientation flights delayed bees in locating nests when they returned. Spatially displacing landmarks had no effects on bees returning to their nests. Nest entrances usually had conspicuous turrets, but these were not required for nest recognition. Turrets provided some cues concerning nest identity since searching bees preferentially contacted their own turrets over alien ones. Swabbing the inner lining of a nest tunnel with hexane significantly delayed the bee's entry into the nest, but distilled water or an equal amount of hexane applied to the outside of the nest had no effect. The delay induced by a hexane wash was reduced significantly by placing the bee's unwashed turret on the nest entrance. Adding whole-body hexane extracts from probably unrelated females to nest entrances significantly delayed bees' entering nests.
A review of mechanisms for nest recognition within Apoidea shows that to date olfactory mechanisms are more prevalent among bees (Apiformes) than wasps (Spheciformes). This pattern may be an artifact of the little information available on wasps. If substantiated, then known cases of olfactory nest recognition generally co-occur with a tendency toward social evolution within Apoidea, supporting a hypothesis proposed by Hölldobler & Michener (1980).