wildebee's Favorites

Please credit photos to NPS/Paul G. Johnson. These bees appeared to be visiting holes on this rarely used dirt road, and there were many hundreds of holes. They seemed to be in areas with a slight slope, not in flat areas. Soil is sand/decomposed granite.

My first guess was B. rufocinctus, but the intensity of the colour and the combined yellow and black bands at the bottom of the abdomen have me wondering about B. sylvicola. And I know there are other possibilities. Unfortunately I did not get a top view of the face and head. Thanks for your help with this id.

Female capping her nest. Took her maybe 3 days to fill the hole (pine, 5/16" diameter, 6" depth). Here's a pic of hotel:

Osmia taurus is native to East Asia, inadvertently introduced to the United States in 1970s along with Osmia cornifrons. This species is apparently one of the first to emerge and can provision young with poor-quality pollen such as that collected from wind-pollinated plants. Seems to be displacing native mason bees for this reason and also (per Packer lab at York University) because mason bee houses are so popular.

(Note: I just altered Establishment Means so that this species shows up as introduced in North America.)