Why don’t my fruit trees bear?

This a question we are asked quite frequently. It could be as simple as too few bees working the trees. Poor fruit set is often a problem in the maritime Pacific Northwest, thanks to our cool, wet spring weather. Orchard Mason Bees to the rescue! These obliging creatures work at temperatures as low as 50°F, and they don’t mind the rain. (Other bees can’t say the same.)

Some fruit trees must be pollinated by insects in order to bear fruit. If you have observed bees on the blossoms in early spring when the temperature is only 50 degrees, then you have witnessed the solitary Orchard Mason Bee at work. The European Honeybee was imported to pollinate fruit trees in the New World, but the honeybees don’t work in cold, rainy conditions! Not so with our native Orchard Mason Bee, which is both hardy AND hard working!

Bees emerge sometime between mid February and early April, depending on the temperature and the blossoming of their food source (bees and blossoms are interdependent). A female Orchard Mason Bee visits more than 1,600 blossoms per day for about 45 days! Because it is a solitary creature (i.e., it does not protect a hive and a queen), you don’t have to worry about having a stinging hive nearby.

To trap and keep Orchard Mason Bees:
• Buy a nesting block with pre-made holes for beds or make your own. The best types come apart so you can harvest the cocoons and then wash & sanitize the system for next season. Good hygiene will ensure more bees. (If you drill holes into wood, use a 5/16” drill bit and don’t go all the way through the wood but do go nearly through).

• Place your nesting block against a warm, south-facing wall by March 1. Bees do best in full sun, but under an overhang or eave that will keep out the worst of the rain. When the female bees emerge, they will look for suitable existing holes in which to lay their eggs. If you have more than one block, place them close together. Orchard Mason Bees are sociable creatures!

• Do not hang nesting systems in trees or on fence posts. These locations are too exposed! (Keep thinking: Warm and protected.) Your bees will find your fruit trees if their nest is within several hundred feet.

• Locate the nesting system near a mud source. The female uses the mud to create separate cells for the eggs she will lay. If you don’t have natural mud, dig a 3-4” deep, 18” wide hole, line it with plastic and fill it with moist soil. If the weather is sunny, remember to add water periodically, to keep up with the girls’ mud requirements!

• Jump-start your nesting system with live bees. The Plant Farm carries live bees when they are dormant and can be sold. The bees are available, generally, from December 1 until the end of March.

• Provide a rich supply of pollen and nectar with plantings of winter-blooming heather, Oregon Grape and Pieris japonica, in addition to your fruit trees. Orchard Mason Bees forage from about March 15 to June 1, so these plants will help prevent your bees from seeking sustenance in someone else’s yard.

• After mid-September you can remove the bee nest systems gingerly to a cool shady shed or garage. This keeps them safe from woodpeckers and other dangers. Mid-October through December is the best time to clean out the nests. It’s then that the bee adults are fully formed & sturdy enough to handle the cleaning process. The book ‘Pollination with Mason Bees’ by Margriet Dogterom will explain fully the cleaning process of the cocoons and nest trays.

In addition to being valuable pollinators, Orchard Mason Bees are also fascinating insects to have in your garden as “pets.” Kids and (kids at heart) love to sit and watch the miracle of the bees’ life cycle, and your bees can establish relatively large populations in 2-3 years.

To learn more about the life-cycle of these bees see the All About Mason Bees Poster at the Mason Bee Display.