Any idea why are these small bees digging in my containers, they seem to pull soil out from the top and also from the bottom.
They are at least half the size of a honey bee and are much quicker in flight than honey bees.
These are actually stills from a couple of videos I took.
I hope someone can identify them.

do they take pieces and fly away with them? or do they tunnel in?

Read that 75% of the bee population are ground dwellers.

sallyg said: do they take pieces and fly away with them? or do they tunnel in?

I have seen them just tunnel in and the excavate soil is just mounding around the holes.

crawgarden said: Read that 75% of the bee population are ground dwellers.

I was expecting burrowing for something like Megachile centuncularis (leaf cutter bee) which is often found in the substrate of containers, or say bumble bees (probably way too big for these containers).

I have not seen these small ones digging before in containers.

I saw them carrying pollen on their hind legs, I would guess they are laying eggs inside the containers and leaving the pollen as food for the larvae.