On one of my last walks in Northern France earlier this week I found two bees fighting. See the video at the bottom. Looking around after I found these mostly solitary bees, under the genus Colletes, or plasterer bees. Here is one emerging from its tunnel. (these are iphone shots, so not great quality).
These bees sometimes nest in aggregations, and I found a hundred or so little tunnels in the sandy cliff near the beach. See these little entrances here.
So what is with the name? These species build cells in underground nests that are lined with a cellophane-like plastic secretion, a true polyester, so they also have the nickname of polyester bees.
And here they are fighting.