The fact that these bees are roosting during the day indicates that they are males - the females are too busy to be hanging around like this!
Classification
Species counts from Australian Faunal Directory
Order Hymenoptera - Wasps, Ants, Bees and Sawflies, 12202 named species in Australia
Family Colletidae - Short-tongued Membrane bees, 883 named species in Australia
Genus Hylaeus
Species ?