Osmia / mason Bee
Female Osmia granulosa Cockerell. © Rollin Coville
Female Osmia on Penstemon. © Rita Clagett
Mating Osmia cornifrons in Ithaca, NY. © Laura Russo
Female Osmia granulosa Cockerell. © Rollin Coville
Family: Megachilidae
Genus: Osmia
Common Name: Mason Bee
APPEARANCE
Physical Appearance
Coloring is usually a dark metallic, ranging from green to blue.
The female carries pollen in a brush of specialized hairs, called a scopa, on the underside of her abdomen.
Characteristics
Osmia species are cavity or tunnel nesters, most making their nests in pre-existing wood tunnels. As opportunists, many Osmia species will readily occupy man-made wood block nests or stem bundles.
To construct brood cells, the female divides her tunnel nest with walls made of mud or chewed leaves, hence the name mason bee.
Osmia are recognized as valuable crop pollinators. Some species, such as Osmia lignaria (blue orchard bee) are now managed to pollinate orchards. Just 250 females can pollinate an acre of apple trees, a task requiring approximately 20,000 honeybees!
Size: Small to medium sized bees, usually less than ½ inch in length.
HABITS
Distribution
A large genus of about 350 species worldwide, found primarily in North America and temperate regions of Eurasia. Osmia species are widespread across North America, though are rare in desert regions. The greatest diversity of Osmia species is found west of the Mississippi.
Number of species in North America
Approximately 150
Emergence Time
Spring to early summer
Nesting Habit
Tunnel nesting, in pre-existing tunnels in wood or in other suitable material. Many species will adopt artificial nests of drilled wooden blocks, reed or bamboo stems.
Pollinated Garden Crops Include
Apple
Pear
Cherry
Plum
Peach
Blackberry
Blueberry
Additional Flowers Visited in Natural Areas
Hydrophyllum (waterleaf)
Rubus (blackberry)
Visited Plants
Geranium / Wild Geranium
