Native Mason Bees for Early Crops – Part I

A lot of the “buzz” about the pollinator crisis is centered around honey bees, and rightly so.  These hard-working and highly social bees are managed worldwide to pollinate many edible and ornamental crops, as well as for their honey production; anything that puts honey bees at risk threatens not only our well-being but our very survival.  However, they are only one part of the pollinator picture.

Oregon is home to somewhere between 400 and 500 species of bees.  Unlike the (non-native) honey bee, most are solitary; while many native bees don’t mind living in proximity to one another (or to bees of other species), they don’t live together in social groups.  All females are fertile, and lay their eggs separately.  Though they provide a food store for each larvae to develop on, they don’t build up long term food storage (honey) to maintain future generations, nor care for the larvae after hatching.  Instead they focus a flurry of activity in their short 5 or 6 week mature lifespan; then the adults die off and the eggs and larvae gestate and develop for the remaining months, to re-emerge in their season the following year.  Different species of solitary bees are active at different times of the year, with some overlap.

Our early spring solitary bees are the mason bees.  In late February and early March, as the daytime temperatures start pushing into the 50’s with some regularity and the Oemleria, Ribes, and Mahonia begin to bloom, mason bees begin to emerge.  At temperatures that leave honey bees huddled in their hives trying to stay warm and dry, mason bees are jaunting about, making frenzied runs back and forth from the few flowers open this early to their chosen nest location.  By mid May they are done, leaving their eggs to hatch and larvae to develop in their nesting holes for the rest of the year.

All this early activity can be very beneficial for gardeners and orchardists.  Not only do a number of our native plants bloom quite early in the spring, but so do many important crops, including plums, pears, peaches, and blueberries.  Because of their cool weather tolerance, mason bees are out pollinating in late February or early March, well before any consistent honey bee activity.  Even later spring bloomers such as apples and cherries benefit, as mason bees start work earlier in the morning and work later into the evening.  Their brief window of season drives them to make many repeat trips to any pollen sources they encounter; this increases the chances of pollination, but does limit their effective distance to just a few hundred feet.  Within this range, they are highly efficient – bee for bee, mason bees out-do honey bees as much as 60 to 1 in pollination effectiveness.

Whether to improve crops, maintain native plant populations, or just enjoy the diversity of our natural world, encourage and manage habitat for our native pollinators today.

Part Two will cover needs and management of mason bees at home.