Nomia bees are, as a group, fairly common in Sydney. They are members of the family Halictidae, which contains around 25% of Australia's native bee species and are (discounting the commercial Honey Bee) the most abundant bees around the world.
Nomia swainsonia is quite common. It is dark brown with golden bands and quite spectacular. A close relative, N. aurantifera, is much rarer and has fewer bands. The Green and Gold Nomia Bee (Nomia australica) is quite large (1 cm) and has white and golden hairs on its metallic blue-green abdomen.
Nomia bees live in urban areas, forests and woodlands, and heath. Most species nest in the ground and a number of females use the entrance and main shaft but dig their own tunnel off to the side.
Nomia bees are found throughout Australia.
Other behaviours and adaptations
During the day male Nomia bees forage for nectar but at night hundreds of them gather together, clinging onto grass stems. Nobody really knows why they do this but it is a behaviour that some other bees, including blue-banded bees, also show. The behaviour of the females is slightly better understood. Up to three share a nest burrowed into the soil. They take turns guarding the entrance, blocking it with their face during the day and their abdomen at night.
Life history cycle
Inside the nest the Nomia bees make urn-shaped cells containing a disc of nectar and pollen and a single egg. Each nest may be reused by several generations.