The red mason bee (Osmia bicornis) is a solitary, cavity-nesting bee in the family Megachilidae, named for its habit of sealing nest cells with mud in pre-existing hollows such as mortar joints, hollow stems, and bee hotels. It is the most familiar solitary bee in British and northwest European gardens, flying from April through June or July (occasionally from late March) on a single annual generation. A polylectic forager, it ranges widely across spring-flowering plants; pollen provisions favour maple and oak, and it visits fruit blossom including apple, plum, and pear, making it a valued pollinator for orchards and kitchen gardens. Mean foraging distances are typically around 100–150 m from the nest, with a maximum recorded range of around 600 m, and its readiness to occupy artificial nest tubes makes it highly compatible with garden habitats across Europe and parts of North Africa and the Near East.

Plants this species pollinates · 1

Nectar plants · 1

Pollen plants · 1

Native across the western Palaearctic: from Sweden and Denmark south through mainland Europe to Spain and Morocco, east through Turkey and the Near East to Iran. Widespread and locally common throughout Britain as far north as Perthshire; established in Ireland since around 2003, currently known from Belfast, Dublin, and Cork. Conservation status: Least Concern (IUCN).