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Mason Bees — True New Yorkers

Flora and Fauna Fridays

A weekly entry about the life of our estuary and watershed.

Hornfaced mason bee by Beatriz Moisset via Wikimedia Commons.


Blue Orchard Bee by Robert Engelhardt via Wikimedia Commons.

Quick! Picture a bee’s home. Most folks visualize a honeycomb, with its elaborate system chambers and complex society in service to a queen. New Yorkers are even prone to compare their dense, buzzing lifestyle to those of drone honey bees. In this increasingly freelance economy where over half of Manhattanites live alone, the mason bee might a more apt symbol. These small but energetic pollinators live alone in individual nests yet packed as close to another as apartment dwellers. It doesn’t hurt their relatability for Knickerbockers that some mason bees are a bit flashy, with metallic coloring.

Osmia georgica mason bee via University of Virgina.

In nature, mason bees seek out crevices, holes bored by other insects, hollow straws, or even empty snail shells. They don’t drill into wood like carpenter bees. The common name for the osmia genus of bee, of which there are hundreds of species, derives from how they compartmentalize their masonry-like nests with walls of grit, clay, chewed plant fibers, and mud. One fancier sort, however, true to Ottoman and Persian opulence, lines its nest with flower petals throughout its range from Turkey to Iran. Each chamber houses an egg that’s laid atop its provisions of pollen and nectar. As each egg is set up, the female walls it off and starts anew. She does this again and again over her six-week life. Females are laid first, in the deepest levels, and males toward the front. The males emerge first and wait for the females to emerge for mating — some might even extract a female. Then the males quickly die.

For all of their diversity, masons comprise just 7% of all bees in New York State. Most other bees live underground, in abandoned animal  boroughs, hollowed out logs, or hives.

Mason bees are not at all aggressive, and their stingers — which lack barbs — evolved to become primarily egg guides. One can even gently handle mason bees without fear of being stung. For this reason, and their high activity (they’re orders of magnitude more efficient as pollinators than honey bees), mason bees are increasingly popular in urban gardens and natural conservation areas. The native Blue Orchard bee is especially solicited, though Japanese Hornfaced Mason Bees were imported and have become naturalized. Other varieties commonly seen in these parts are the Bufflehead Mason Bee (Osmia bucephala), Bull Mason Bee  (Osmia taurus), Hoplitis Mason Bee, Osmia Georgica Mason Bee, and Osmia Pumila Mason Bee. We’ll encourage these bees to strengthen HarborLAB’s shoreline plantings of native flowers and fruit bushes that stabilize shorelines and sustain migratory birds and other wildlife.

To welcome mason bees, some folks purchase commercially made houses made from bundled tubes. HarborLAB uses a different and equally proven design: “bee blocks.” Volunteer Jessica Grable, who leads our fabrication projects, provides wood in three pieces: a block with an angled top, a small piece to be nailed on that slope for a rain roof, and a thin mounting plank. Students and volunteers nail those pieces together, paint only the roof, and use a manual drill to make rows of holes for the bees to occupy. Some designs are more elaborate, drilling deeper holes into larger blocks (6″ is ideal) and lining them with parchment paper. These measures are generally taken by farmers and serious gardeners. We’ll experiment with different forms, and perhaps even try using invasive phragmites reeds.

Our mason bee homes will be donated to waterfront parks, gardens, and wilderness areas throughout NYC. One of our first installations will be the historic and beautiful Old Stone House near the Gowanus Canal. We’ll of course erect them all around our home waterway, the Newtown Creek!

Prototype mason bee home by Jessica Grable.

Tips for placement:


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