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Hundreds of holes on rudimentary mud/clay brick structure, dozens in flight entering/exiting and hovering.

Clearly, not all holes are in use. Groups of active holes are restricted to specific bricks, some bricks show no activity whatsoever. Must be several seasons worth.

Keys discretely to O. cordata via Mitchell (1962), Discoverlife, and Sandhouse’s ancient (1934) key to subgenera and species. Aligns with all available descriptions. Diagnostic features pictured include coarse and often contiguous/confluent punctures of scutum, golden scopa, facial features (including mandible/flat clypeus rim), narrow but definite impunctate area along apical rims of terga, evenly pubescent terminal tergite with fine punctures and without an apical fascia. Several individuals were visiting Penstemon digitalis. They either had deeply yellow, yellow-orange, or even rust-yellow scopa, further fitting with available descriptions.

I also found O. albiventris at this site; I show it side by side a cordata to demonstrate the differences in punctation and size; I also photographed it beside an O. pumila for additional size comparison. Osmia cordata clearly differs from the two, and its mandible (pictured) also clearly fits with the form drawn by Sandhouse (1934), separating it from O. sandhouseae. In the Discoverlife key, sorting by yellow scopa and flat clypeal margin was sufficient to get to cordata. T6 was not fasciate, ruling out conjuncta/subfasciata; the lack of a tuberculate space between antennae also disqualified conjuncta for this series.

I think a first record for TN. However, a certified record occurs just over the mountains in NC (bowl trap; GBIF), so this TN specimen still seems to fill into the range sensibly. Mitchell (1962) says Colorado to Ohio.

Collected on Mock Orange that lines a steep roadside escarpment ~20 meters.

This bee has all of the key diagnostic features expected for Andrena cerebrata: photos show the the nearly bare scutum, covered with only fragile and sparse or tiny hairs; long narrow foveae; a present but weak pronotal angle. All other features are as in the diagnosis and description on Discoverlife.

This female keys to Andrena gardineri in Mitchell (1960) and LaBerge (1967); also, to Callandrena in LaBerge (1985)’s subgeneric key. A tad early for this bee, but iNaturalist observations at this site show Packera is well into bloom by now.

Selection of initial characters in Discoverlife also leads to A. gardineri, A. hirticincta, A. rubi, and A. rudbeckiae; it cannot be the latter 3 for numerous reasons, especially the flight season and facial characters.

I attempted to photograph the bidentate labral process, hyaline tergal rims, among other key cool features of this bee.

Keys to Andrena erythronii. Pictures show a distinct but weak pronotal angle, flat clypeus with median impunctate line, wide but slightly emarginate labral process, impunctate abdomen without strong fasciae, linear malar space. Foveae are ~2/3 space, propodeum is not rugose or striate as in Trach/Scrapt. Pale vestiture, nothing fuscous or black.