Pollinating Orchards and Berries with Mason Bees

A male mason bee is attracted to the scent of last year’s cocoons – the smell of success (all photos by D. Cahill.)

Buying or trapping blue orchard mason bees may be a good plan for your spring-blooming orchards’ pollination needs. Mason bees are affordable, low maintenance and improve crop yields. The little bees work well in conjunction with honey bees in almonds, cherries, pears, early raspberry varieties and blueberries. Researchers are starting to also look at mason bees’ pollination effectiveness in strawberries, too.

Unlike the European honey bee, mason bees are native to the US. They emerge in early spring, with males emerging first. They set about pollinating while keeping an eye out for females. Females emerge several days later. Males live two to four weeks, while females live six to eight weeks.

Retired entomologist Rich Little, a former county deputy agricultural commissioner in California, suggests farmers place 20 to 30 mason bee boxes per three acres. That many, he says, is manageable for one person.

“You have to scatter these boxes throughout the grove,” Little said. He keeps 15 to 20 mason bee boxes at his home in Sweet Home, Ore., and gives educational programs on native bees through the Oregon State University Extension Service.

As far as what the little iridescent blue-green mason bees require: “There needs to be food and there needs to be mud,” Little said.


Cocoons with emerging mason bees.


Steps for Mason Bee Success

Watts Solitary Bees, located out of Washington state, offers the follow steps for success with mason bees. The company sells bees to farmers with commercial customers in Idaho, Washington, Oregon and California. Almond growers are one of the company’s biggest clients and Watts estimates almond growers can replace one hive of honey bees per acre with 1,000 mason bees.

“We did 1,000 acres of almonds last year with mason bees,” said owner Jim Watts. “The almond growers are paying huge amounts for pollinators. Honey bee prices are going up every year.”

Watts offers the following advice:

1) Trap or purchase wild mason bees.

2) Set out nesting material throughout the orchard, including football-sized balls of wet clay.

3) Incubate the bee cocoons until time for release.

4) Provide forage for food and mud for nest building.

5) Check on bees during the active season.

6) Remove bees from the orchard after pollination.

7) Sanitize cocoons and bee boxes.

8) Store the cocoons over the dormant season.


Retired entomologist Rich Little demonstrates how a wooden bee box opens for cocoon removal.


Protecting Bees from Spray

Mason bees are more susceptible to sprays than honey bees, according to Watts.

“Tank mixing sprays together is really detrimental,” he said, adding that it’s important for farmers to learn how to protect their orchard without killing the bees. “It’s really more about what you spray, when you spray and how you spray it.”

Watts said they put the nests inside totes. Before farmers spray, they can simply put the lids on the totes if they choose.


A male mason bee has just emerged from his cocoon inside a hatching box.


Pests of Mason Bees

Pollen mites hide out in flowers and hitch a ride on mason bees back to the nest. That’s why cleaning the cocoons before storage is important.

Houdini flies are also a serious pest to mason bees. They came in from Europe. Watts cautions growers to buy their mason bees from reputable and preferably certified bee farmers. Otherwise, he said, growers could accidentally buy tubes full of Houdini flies and spread them to native bee populations.

Watts Solitary Bees has its bees and equipment inspected as part of the certification process.

“We’re getting better and better at it,” Watts said of his family’s operation. Even so, he knows there is still room to learn more. “Ten years from now it may be way different.”

Watts also predicts the current price for mason bees–which started out at $1 a bee and has since dropped to 30 to 40 cents–will eventually fall to about a nickel a bee.

There was a definite learning curve involved in farming mason bees, Watts said. His family has another division of the business called Rent Mason Bees, which rents bee kits to backyard gardeners. In June, the gardeners ship the filled bee boxes back, where the cocoons are cleaned and stored for the following year.

It took eight years, what felt like forever,  to get production to 1 million bees, Watts said. “Then it started snowballing.”

Watts’ advice to growers who want to try mason bees for the first time? “Get help. It’s not hard, but what we do has a lot of science behind it. You need to get help early,” he said. Watts provides on-site consultation, a service that is built into the price. “It’s actually not too early now to get started,” he added.

It’s helpful to the bees to have other blooming plants in the orchard. In almond orchards, for example, Watts suggests growers plant a mustard mix every row or every other row. “It will bloom along with almonds, and about a month later.” The bees prefer the tree blossoms, so they’ll head there first. The mustard will give them enough to sustain them after almond bloom. Planting native shrubs and flowers around fields and orchards also helps.

Food pollinated with mason bees can be marketed as “pollinator friendly” or “pollinated with native bees.”

“The future of mason bees, I think, is really bright,” Watts said.


Rich Little inspects a hatching box.


Mason Bees vs. Honey Bees

According to Watt, it takes fewer mason bees to pollinate a crop. It takes only 400 mason bees to do the pollination work of 40,000 honey bees. Honey bees are a more advanced bee. It takes about five contacts with a honey bee to fully pollinate a bloom. Mason bees are more primitive.

“Mason bees are messy like a kindergartner,” Little said. A mason bee isn’t elegant at landing—she sort of belly flops into the flower. “She gets pollen all over her body. One contact with a flower and it’s pollinated.”

Little said honey bees are fair weather workers and don’t like to fly during wet or cold weather. Mason bees work in cooler temperatures and even during light rains. They often also work longer hours from early morning until late in the day. While honey bees will fly several miles to reach food, mason bees only work close to home. They travel in a 300- to 400-foot radius from their nest, about the distance of a football field.

Unlike honey bees, Mason bees rarely sting. They have an ovipositor for laying eggs, and although the females can sting with it, they rarely do. If you smash a mason bee or get one trapped in your shoe or clothing, it will likely sting. Otherwise, they are harmless, safe even around children and pets. They may bump into someone standing in front of their bee box, but most of the time will simply fly around you. Honey bees, on the other hand, have a communal hive and a queen to protect. They will sting if roused or disturbed.

Mason bees don’t make honey. They collect pollen and nectar, which they leave in a ball with a single egg per cell. It’s just enough for the larvae to survive on before chewing their way out of their cocoon the following spring. They also have a short lifecycle. The males survive only a couple of weeks. Females live six to eight weeks. Their lifecycle matches well with early blooming crops. Mason bees aren’t around to pollinate summer-blooming crops. Honey bee workers generally live from six weeks to six months and work a longer season from springtime until cold weather sets in.

For more information about Watts Solitary Bees, go to www.wattsbees.com.


A female mason bee peers out from her nesting tube.