Last winter, I created a page for the solitary bees I photographed in my garden the previous spring and summer. At that time, I didn’t have any shots of mason bees. Most of the shots I did have were just dumb luck: I accidentally got photos of bees while I was focusing on flowers. This spring, I knew what to look for, and I wasn’t disappointed. The mining, mason, and carpenter bees were the first to appear, and they visited the viburnum, crab apple, and other flowers that opened early in the season.
Mason bees belong to the genus Osmia in the family Megachilidae. Mason bees are named for their habit of using mud or other similar materials to construct their nests in naturally occurring gaps such as cracks in stones or other small dark cavities.
Mining bee
I really like the mason bees. They are smaller than honey bees and shy. It’s not easy to get close for a clear shot. The Megachilidae family also includes wool carders, leaf cutters, and resin bees. Bees in this family are all solitary, and they have one very interesting physical trait in common: they carry pollen on their abdomens instead of on their legs with special hairs called scopae. Here you can compare the scopae (pollen basket) of the mason bee to the leaf cutting bee.
Pollen broom (scopa) on leaf-cutting bee
Three types of mason bee are common in Pennsylvania. According to Penn State Extension, two species in the genus Osmia are currently being used on a limited basis for tree fruit pollination: the blue orchard bee (Osmia lignaria) and the Japanese orchard bee (Osmia cornifrons). The latter was introduced by the USDA into Mid-Atlantic region fruit orchards from Japan in the 1990s. Another Japanese bee, Osmia taurus, was found in Maryland, although this species was not introduced intentionally and therefore was not quarantined for parasites and pathogens. O. taurus is very similar in appearance to O. cornifrons. Look for long, widely spaced horns on the face of O. cornifrons. However, according to bugguide.net, it is not always possible to distinguish the two species based on photographs.
So the shots below could be either!
In May, I saw the blue orchard bee only twice. They are black with a metallic blue sheen, and a dead giveaway is the fluffy scopae on the abdomens of the females.
Since my quest started to identify more insects in the garden, I’ve also photographed the Osmia Georgica. The Georgia mason bee can be found from Massachusetts to Michigan, south to Georgia and Texas and it is seen from March to August. It has been recorded on multiple types of flowers including brassica, chrysanthemum, erigeron (shown here), lupinus, malus and others. They are a dark metallic color like the blue orchards, but they have striped abdomens. John Ascher at bugguide.net helped me with the id.
Only one mason bee has found the houses so far, and it was a blue orchard. I hope they fill up soon.
To support mason bees, plant varieties of shrubs and perennials that flower early in the season when they begin to emerge. Some choices include
- False indigo
- Wild geranium
- Virginia bluebells
- Phlox
- Foam flower
- Golden Alexander