BB bees roost on 2 stalks in our suburban herb garden. They arrive about 6:30pm and roost until sun warms them after 08:00am. They are creatures of habit - 7-9 bees have returned for the past 5 nights. Even on windy evenings they persist and eventually settle. Web search suggests these are all male bees. The plant stalks are introduced species - spent flower stems of Oregano herb.
Some of this group kept coming 'home' to roost for about 4 weeks after the first sighting. Eventually there were just 1-2 insects each night and the cold and wet weather appeared to mark the end of the roost. Warm evenings since then have seen no new visits.