Miner bees are an entertaining lot...... at least I think so. For instance, I thoroughly enjoyed watching this miner bee...
Mining bees (Andrena spp) and Cellophane Bees (Colletes) have lots of hair and smokey wings...
Maybe "cluster" or "aggregation" is a better word than "colony" because they are solitary bees but they don't mind living in close proximity to each other.
These bee nests remind me of the mine dumps from old mines like this one pictured below(right). This is the headframe of the Yankee Girl Mine near Red Mountain Pass along the Million Dollar Highway north of Silverton, Colorado.
While I was observing the bees' nests there were some small, reddish bees patrolling around in the vicinity. When I take the kids to explore the "mines", I hope they notice these other bees and wonder, "What's up with that?"
Miner Bees mini series, part one.
Miner Bees mini series, part three.
P.S. Please note that when we dug open one of these nests we discovered that the bees were not miner bees, but Cellophane Bees.