The genus Tetrapedia contains approximately 13 species of small apid bees occurring in the Neotropics (from Mexico to Argentina), and they are unusual in possessing adaptations for carrying floral oils rather than (or in addition to) pollen or nectar. They don't seem to be known to ordinary people, and apparently lack a popular name.
Where I live, this aggregation of males on the plant “Barba-de-velho” (Tillandsia usneoides) is recurrent. The bees drink the rain and sway violently in the wind during storms. On cold days, they don't even go out for their daily chores. I'm surprised they haven't become easy targets for birds yet.
