Ground bees. They were going in and out of holes in the ground. The big bee in #2 is posted separately.
Bee visiting this plant: https://www.inaturalist.org/observations/100455721
When approaching a flower, the bee made a loud buzzing sound and some pollen was released (the falling pollen can be seen in picture #5). There were several individuals at the same time, together they made quite a loud noise. They went away and came back several times.
Registrada enquanto se alimentava nas flores de Lepidaploa aurea (Asteraceae, Vernonieae) na Reserva de Cerrado da UnB (APA do Lago Paranoá).
Registrada enquanto se alimentava nas flores de Banisteriopsis sp (Malpighiaceae) na Reserva de Cerrado da UnB (APA do Lago Paranoá).
Bee digging tunnel in sand. Would remove material from hole by moving sand backward. About 12 mm in length.