המועדפים של brianalindh

up to 8 of these would bunch up in a tight group. with half a dozen others flying in and out and landing within half a meter. No flowers around, jutrocky ground alongside the road. No visible hole in the area. some red ants were coming upand bothering the bumblebees, and as you see in one photo, an apparent Andrena bee came up to the group. This milling around went on for at least half an hour, which is when I left. No noticeable attention being paid to any particular individual. All seemed healthy.

Found in Fernbank Forest. Bees were concentrated on the underside of a group of leaves of a beech tree. Tried to do some digging and my best guess is that this is a lek. Based on the overall size and the fuzziness of the foveal area my best guess is this genus.

I watched two of these insects digging in the dirt below small rocks, on the uphill trail, right before Mitchell Rock, Mount Diablo State Park. The second image is of the the bee turning its body 360º (top to bottom). This insect appeared to match Blue-and-black Mining Bee (Andrena nigrocaerulea), but I have no knowledge of what other species may be considered.