Compact, dark bee with white-striped abdomen. No pollen, but long hairs on the underside of abdomen. On Centaurea stoebe flowers in disturbed draw, gently south-facing. Smoky afternoon, sunny, light breeze, 62 F to 69 F. Disturbed, rocky grassland community north of the stream with a mix of native and non-native vegetation.

Elevation ca 4000 feet. Disturbed riparian corridor on stream restoration site within a patchwork of native and non-native grassland.

No arolium between the tarsal claws, eliminating Osmiini; lacking the yellow coloration of Anthidiini. Abrupt angle of first tergite in lateral view, combined with the lack of arolium and yellow coloration, point to Megachile. Unfortunately I did not get a well-focused photo of the mandibles. However, the mandibles appear sculptured - perhaps distinctive to a species or group of them?