Photo: Anatole Maugendre / CC BY-NC

Osmia rufohirta

Red-haired Snail-shell Bee

A small mason bee (8–9 mm) with distinctive reddish-fox coloured hair on the thorax and a compact body. It is a generalist (polylectic) forager but shows a preference for Fabaceae (clovers, sainfoin, bird's-foot trefoil). It is famous for its unique nesting behaviour: it builds its nest inside empty snail shells, particularly of Helicella species. The female constructs a single brood cell per shell, seals it with chewed leaf pulp mixed with small pebbles, and often hides the shell under vegetation. It is univoltine, flying from May to July. In Switzerland it occurs in dry, warm, calcareous habitats such as dry meadows, rocky slopes, old vineyards, and ruderal areas in the lowlands and Jura mountains. It is classified as vulnerable on the Swiss Red List.