Orchard Mason Bees
Osmia lignaria is an Efficient Pollinator
Jan 17, 2009 Stephen Allen Christensen
Most of the world's orchard, horticultural, and forage crops can only produce seeds and fruit if animals (birds, bats, insects, etc.) actively transfer pollen from one flower to another within the same species. The Food and Agriculture Organization of the United Nations estimates that of the 100 crop species that provide 90 percent of food supplies for nearly 150 countries, 71 are bee-pollinated, mainly by wild bees. (FAO Spotlight, December 2005)
The recent decline in honeybee populations has emphasized the relative significance of other bees. The blue orchard mason bee (Osmia lignaria) is one of many species of wild bees that are vitally important to pollination and, hence, to human wellbeing.
Orchard mason bees are native to the United States. Two subspecies are represented, with O. lignaria lignaria preferring the higher humidity found in the east and O. lignaria prorinqua being more adapted to arid western regions.
Orchard masons are solitary bees: They do not congregate in hives with dominant queens, nor do they produce honey. However, several females may use nesting sites that are within close proximity to one another.
Although orchard mason bees can sting, they rarely do so. Unaggressive and innocuous, they usually go about their work unnoticed.
Individually, orchard mason bees are more proficient pollinators than honeybees due to differences in pollen-collecting habits and activity levels. When conditions are favorable (i.e., proper humidity, sufficient forage) orchard mason bees tend to stay within 200-500 yards of their nesting location. Honeybees, on the other hand, may travel several miles from their hives.
Life Cycle of the Orchard Mason Bee
Osmia females prefer to nest in hollow tubes (reeds, predrilled cavities left by other insects or birds, etc.). They favor holes with a diameter of 7-8 mm (approx. 5/16 inch). Orchard mason bees do not bore holes in wood to lay their eggs.
- In early spring, after selecting a nest, the female bee places a mud plug at the back of the tube (hence the name “mason”) and then deposits a packet of pollen and nectar in front of the plug. A single egg is laid on the packet, and the chamber is sealed with another mud plug.
- This process is repeated until the tube is filled with 6-8 separate cells. Eggs that will develop into females are placed at the back of the tube, while male eggs are placed near the exit.
- Eggs hatch a few days after laying, whereupon the larva begins to feed on the nectar/pollen reserves. When its food is consumed (in about two weeks) the larva spins a cocoon and pupates until late summer.
- Emerging from its cocoon as an adult bee, the orchard mason hibernates inside its chamber through the winter, living on the fat stores it developed as a larva.
- When temperatures reach the mid-50s (F) the following spring, the bees chew through the mud plugs and emerge from the nest. Males emerge first and await the females’ appearance.
- Mating occurs soon after emergence. Males die almost immediately after mating, while females forage and lay eggs for another six to eight weeks.
Orchard mason bees are being widely cultivated to take advantage of their pollinating skills; while it is possible to purchase bees to establish a colony, placement of nesting boxes will often attract local wild populations.
Sources of Orchard Mason Bees and Supplies:
References
1. Bosch, J. and W. Kemp. 2001. How to Manage the Blue Orchard Bee. Sustainable Agriculture Network, Beltsville, MD. ISBN 1-888626-06-2
2. Batra, S. W. T. 1984. Solitary bees. Scientific American 259:120-127
3. Kemp, W.P., Bosch, J. 2005. Effect of temperature on osmia lignaria (hymenoptera: megachilidae) prepupa-adult development, survival, and emergence in the orchard pollinator. Journal of Economic Entomology. 98(6):1917-1923
Blue Orchard Mason Bee
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