Observed in a Sidalcia sparcifolia flower. I came across Osmia lignaria ssp. propinqua in iNat but only four recorded in SD county. (Spider mite in #8 is incidental as it never shows up in any other photo.)
1217, 67F, sunny, 7 mph
1223, 67F, sunny, 9 mph
Really aggressive. Got stung and pursued for another 25 yard up the trail! second photo is stinger pulled out of my face!
Female emerging from her nest hole (in reverse order)