Ynghylch

Male red-tailed mason bees appear early in spring, usually in early March, with the more distinctive females emerging a week or two later. They're most at home on chalk and limestone grasslands, quarries, and brownfield sites. They can be seen visiting a range of flowers, from bird's-foot-trefoils and vetches to spring-blossoming shrubs like sallows, blackthorn and hawthorn.

Red-tailed mason bees have the unusual habit of nesting in empty snail shells. Females lay their eggs inside a shell then plug up the opening with pieces of chewed up leaves, soil, and shell fragments. They then collect grass stalks and other items to place in a mound on top of the shell. This is probably to protect their eggs from predators and parasites.