Not all bees live in colonies with a queen; there are also solitary bees. These have individual nests, albeit close together, and all females are fertile. Some of these solitary bees live underground, and those can dig holes surprisingly quickly.
Here are a few nice photos of these mining bees. The first three are called grey-backed mining bee (Andrena vaga), grijze zandbij in Dutch:
This one is a hairy-legged mining bee (Dasypoda hirtipes), pluimvoetbij in Dutch:
Friendly little animals, these are, and fun to watch at work.
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