[2] Osmia bicolor females are small bees, 12 mm in length, with a black head and thorax and an abdomen covered in bright ginger hair.

[1] Osmia bicolor is univoltine in western Europe and is among the first bees to emerge in the spring, males can be seen as early as February,[4] although the normal flight period is from April to July.

[2] Once the female has selected a shell she moves into her preferred position before depositing balls consisting of chewed up masticated pollen and nectar to provision the nest.

[4] Male O bicolor have been recorded using empty snail shells as shelters during periods of cold or wet weather and at night.

In Britain it has been recorded as feeding on wood anemone (Anemonoides nemorosa), common bluebell (Hyacinthoides non-scripta), heath dog-violet (Viola canina), bird's-foot-trefoil (Lotus corniculatus), horseshoe vetch (Hippocrepis comosa), sainfoin (Onobrychis viciifolia), willow (Salix spp.