Nomia bees roosting

Nomia Bee, Lipotriches Australica. Nomia bees nest in burrows in the soil. However, at night large numbers of male bees cluster together on grass type vegetation. Here they are roosting on Gaura Lindheimeri in my garden. Various species of nomia bees occur in all states of Australia. They gather in quite large groups on the ends of grasses and long stems, like this gaura, for protection from climbing predators during the night.