Red Mason Bee

• GeneralSolitary and with no effective sting; it pollinates fruit trees better than the honeybee and nests in holes and hollow stems.
• comportamientoIt builds solitary nests, sealing cells with mud inside crevices or hollow stems, and forms no social colony as honeybees do.
• It does not dig its own tunnels: it makes use of existing holes in stems, old wood, soft mortar, the tubes of insect hotels and even door locks.
• The females mate only once and can decide the sex ratio of their offspring according to their own body size: the larger ones invest more in female eggs.
• It is a commercial pollinator of fruit trees, especially apples, alongside O. cornuta and O. lignaria. A single failure has serious consequences: if a female dies before finishing her nest, nobody finishes it for her.
• It is the solitary bee most widely used as a managed pollinator in Europe, and the main occupant of so-called insect hotels.
• It pollinates fruit trees far better than the honeybee: it carries pollen dry on the underside of its abdomen, not packed into pollen baskets, so it falls off easily and ends up on more flowers. It is estimated that a few hundred females can pollinate a hectare of apple trees.
• The female builds a row of cells inside the tube, each with a ball of pollen, an egg and a mud partition, and seals the entrance with a final plug.
• And she controls the sex of her brood: she places the female cells at the back and the male cells near the entrance, so that if a predator attacks the tube it takes the males first, as they are more expendable.
• It is completely harmless: it almost never stings and its sting barely pierces the skin.
• It flies at lower temperatures than the honeybee, which makes it valuable for early-flowering fruit trees.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat & environment

Hedges, orchards, gardens and woodland edges

Litter / clutch size

One egg per cell. The female fills each chamber of a pre-existing cavity with pollen and nectar, lays an egg and seals it with a mud partition, repeating the process until the hole is full. The final partition is thicker than the previous ones

Sources consulted: IUCN Red List (Lhomme 2014, e.T19198431A21154926); Natural History Museum (Londres); Sedivy et al. 2012, Biological Journal of the Linnean Society 108; Zurbuchen et al. 2010, Journal of Animal Ecology 79; Michener 2007, The Bees of the World; Proyecto Osmia (ADV Ecològica)

Best time: From spring to early summer, coinciding with the flowering of the fruit trees