by Chris Uhtoff Native Bees are important pollinators of wild and commercially grown plants. There are around 4000 species of native bees in North America. 3/4 of all native bees are solitary where the female alone lays the eggs and provides food and a protected location for the eggs to develop. Most native bees create nests in holes excavated in loose soil. But around 1/3 of native bees make their nests in holes in wood made by beetles, wasps and other insects. These holes provide a protected environment that allows the eggs to develop.
The Blue Orchard mason Bee Osmia lignaria is a wood nesting bee and is widespread throughout North America. It is a gentle dark bee that looks very similar to a large plump housefly. The adult blue orchard bees emerge from their holes between February and April and are important early season pollinators of fruit trees and shrubs. The adult male stays near the hatching site to mate with any females. The females collect pollen and lay their eggs during the following 4-8 weeks. The female finds a suitable hole, lays an egg at the end of the hole then adds a pollen and nectar rich food called bee bread for the larva to feed on. This assemblage is walled off with bits of mud. This process is repeated until the wooden tube is filled with a series of eggs and bee bread. During the summer the egg hatches into larva which then forms a protective cocoon inside which develops the adult bee. Some bee species hibernate in the cocoon stage to finish development in the spring. But in the case of the Orchard mason Bee the cocoon stage is completed by the end of summer and the bee hibernates as the fully formed adult. Thus they are able to be active earlier than other bees.
Adding mason bee houses to your yard provides suitable homes for these and other important wood nesting bees and can significantly increase the pollination of fruits and vegetables.
Bee box placement: boxes should be between 2-6 feet from the ground to allow easy access for care and cleaning. Attach the box firmly to a area protected from rain and wind. Blue Orchard Bees seem attracted to buildings so under eaves of buildings provide a good location. The best locations are east or south-east facing to receive early morning sun, so hatching bees can warm up early in the day, yet is sheltered from midday sun which may be too hot. Bees need mud to make the interior walls so exposed damp soil near the nesting box is important.
Care and Maintenance: Every three to four years the bee box should be sterilized to prevent large populations of bee parasites to develop in active nests. To do this place the bee box in darkened box with only a 1/2 inch hole that allows light in, which the bees will use to escape but will not return and refill the box. Once the holes have emptied soak the box in a 5% bleach solution to kill any parasites and you may wish to re-drill the holes with a 5/16 sharp bit. If you use straw inserts you usually do not need to sterilize the box simply remove and dispose of used empty straws. Do not use plasticized straws as these can cause moisture buildup and mildew.
Further information: The USDA operates a bee laboratory in Logan UT they have an extensive Internet resources at www. loganbeelab .usu.edu/. The Xerces society has a very useful website at; www.xerces.org.
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