Mason bees pollinate flowers, trees, vegetables

February 8, 2012
Unlike carpenter bees, the mason bee cannot drill holes in wood. SOURCE SUBMITTED

February is a time of romance - a time of the birds and the bees.  Sadly, Colony Collapse Disorder has recently killed many of America’s honeybees.  Many farmers and gardeners need honeybees for pollination, but don’t need the expense and labor of keeping honeybee hives year-round. Enter “Osmia lignaria,” the orchard mason bee.

The female orchard mason bee collects pollen and nectar, then lays an egg on the ball. True to her mason nickname, she uses mud to build cell partitions and repeats this process until the nest or tube is filled and capped with mud.

The mason bee lays eggs that will hatch the following spring. It lays female eggs toward the back of its home and male eggs toward the front.   Because of this, care must be taken if you are building your own blocks so that the holes are not too narrow, producing mostly male bees.

Each female orchard bee lays about 30-35 eggs. The new bees live for just six to eight weeks after they hatch the following spring.  They hatch when there is food, during the heaviest fruit-tree blossoming season.  Once hatched, they don’t roam very far and usually stay within 100 yards of where they hatch.

Unlike honeybees, the tiny blue orchard bees are not susceptible to colony collapse.  They are gentle, nonaggressive and non-destructive.

Though the bees are native to many parts of North America, many gardeners buy bees to establish a colony.  You can order from companies such as Territorial Seed ( or Miller Nurseries (

Since they are nonsocial bees, they don’t build hives or produce honey.  They do, however, pollinate flowers, fruit trees, nuts and vegetables.

Unlike carpenter bees, the mason bee cannot drill holes in wood.  In the wild, it nests in hollow stems of reeds, in holes drilled by woodpeckers and existing insect holes found in trees or wood.

Each bee nest is separate much the way each bird nest is separate, though in huge groups on nesting rocks.  The mason bees do not share nests and do not protect each other’s young.

Because they are not aggressive, you can observe them at very close range with little worry of being stung.  After about two months, the adult mason bees die, leaving larvae growing and making cocoons, and then growing into new adults.  They stay inside their cells hibernating until spring.  To prevent them from emerging too early and dying in the winter they need cold temperatures before they break their dormancy.

You can build a wooden block nest by drilling holes on three-quarter inch centers in untreated four-inch by six-inch lumber. Holes should be four to eight inches with a five-16th-inch diameter. Do not drill completely through the wood block. Attach a board as a roof to keep out the rain and hot midday sun.

Face nesting blocks toward the southeast to catch morning sun, at least three feet off the ground. Be sure they are steady and firmly attached to a post or tree so they can’t sway in the wind.

Do not move your nesting blocks until late summer or fall when the bees are through nesting. You can then move the blocks to a protected area such as a shed or unheated garage, or leave them outside if they are protected from strong winds and cold.

In romance and in mason bees, time is of the essence.  Many suppliers ship only in February.   Once February passes, Cupid and mason bees won’t be around for another year.

Paul Barbano writes about gardening from his home in Rehoboth Beach. Contact him by writing to P. O. Box 213, Lewes, DE 19958.


  • Paul Barbano writes about gardening from his home in Rehoboth Beach. Contact him by writing to P. O. Box 213, Lewes, DE 19958.

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