Posted on Mar 05, 2020 | by Kerry Kelley
Most of us know by now that bee populations are in dangerous decline. Concerned gardeners have responded with increased interest in pollinator gardens, native plants, and organics, and in the chemical “friendliness” of purchased plants—wanting to be sure they’re safe for their busy little guests. It takes a little research, but it’s simple enough and something we all can do.
Then I saw that some folks even set up “bee motels,” with nesting tubes for certain species, like mason bees. That got me curious. I mean, I love bees as much as the next gardener, but why would one go through all that without the prospect of at least getting some honey out of it?
Aren’t those bees going to damage your house and sting you if they get too close? Isn’t it just plain dangerous to have bees nesting near your home? Ok, some of you educated bee aficionados are laughing at me. But for the ones of you that might not have heard the buzz, after a little research I am prepared to admit--mason bees are pretty cool, and I am excited at the prospect of being a bee landlord.
My first stupid assumption was that mason bees would cause damage. I’ve seen carpenter bees drill big holes in wooden beams, so I figured mason bees must drill holes in mortar or something. Well, they don’t. They don’t make holes at all. They rely on already existing holes made by wood-boring insects, in the hollow stems of plants, or crevices in bark or rock. If the right home isn’t there, they don’t move in.
All right, so they won’t eat my house. But they’ll sting me, right? Mark that stupid assumption number two. Mason bees are fairly docile and at times may even accept gentle handling without complaint. Males don’t have a stinger. And in the unlikely event the female does sting, their venom is quite mild--akin to a mosquito bite.
But still, if they’re living there, and someone gets too close to their nest, there’s that whole protective bee swarming thing, isn’t there? Perhaps it's all the Winnie the Pooh I watched as a child, but I believed this was just a “bee thing.”
It’s not. Not all bees are social, living, working, and chasing humans and imaginary bears around in a cooperative mass. In fact, most native bees are solitary, though females are often happy to nest near each other. The male mason bee is designed to live just long enough to perform his one useful task—mating--so he’s got other things on his mind. Mason bees don’t have the social structure necessary, let alone the inclination, to chase you into the frog pond.
The female mason bee is a fascinating, industrious, independent creature—locating and preparing a home and stocking it with food for her upcoming brood, all on her own. She won’t live until the following spring when her kids emerge from their nest, but she’s an incredible single parent all the same.
On average, she will need to make 40 trips back and forth from the nest for each egg. On each foraging trip she may visit up to 75 flowers, pollinating as she goes. In between each egg and its food supply she builds a protective wall formed from mud she collects and carries to the nest in her jaws.
In the four weeks she lives, she’ll fill as many holes as she can, usually laying 1 to 2 eggs per day. No wonder she’s not aggressive—she can’t afford to waste the energy!
Ok, bee, you have won my undying respect and admiration, and an apology. You are awesome, and I’d like to help you out, too. If aiding these incredible creatures appeals to you also, see our products and tips below:
Our Mason Bee Products:
Tips for Happy Mason Bees:
- Nesting holes should be 5/16” in diameter and no less than 6 inches deep, not drilled all the way through--the back must remain closed. The depth is important, as the female will lay fertilized eggs (which will become females) in the back of the nest, and unfertilized (male) eggs toward the front. This leaves the female eggs well-protected, ensuring the higher number of female bees necessary to maintain the species.
- You can use drilled blocks of wood, bamboo tubes, or pre-made kits with cardboard nesting tubes. If your nests cannot be cleaned at least every 2 years, they should be replaced. This prevents the spread of insects and disease.
- Mason bees key on patterns, especially in blue and black colors, to navigate back to the proper tube. Painting the shelter, and painting the ends of the individual tubes and arranging colors randomly will greatly assist them in finding their way.
- Place your nests 4 to 7 feet off the ground, facing east or southeast, as bees need warmth to be ready to fly. Keep from hot sun in summer--south or southwest are exposures not recommended as developing bees may literally fry. Be sure nests are protected from wind and rain--place under eaves or in a shelter.
- Mason bees are active early in the season, so be sure you have flowers for them to feed on, within 200-300 feet of the nest. Early blooming flowers of the aster family are especially favored: Centaurea (cornflower/bachelor button), Erigeron (fleabane), Bellis (English daisy), Achillea (yarrow), and Antennaria (pussy toes). Annuals you might plant early include Ageratum, Bidens, Osteospermum, marigold, Calendula, Argyranthemum and gerbera daisy. Many orchards home these bees to aid in pollination, as their nesting activity coincides with flowering of apple, cherry, pear, peach, plum, and blueberry crops.
- Mason bees use mud to seal off the egg chambers, so be sure there's a handy supply near the nest. If your soil is sandy, set out a dish of wet clayey soil for them to gather.
- Mason bees will pupate in summer, and winter over as dormant adult bees, to hatch as temperatures warm to about 50 degrees in the spring. To keep your sleeping beauties safe from predators and disease, it is recommended to harvest and clean the cocoons in the fall. It's simple, and takes about 10 to 15 minutes. Gently open the tubes and separate the cocoons from the nesting material, destroying any C-shaped cocoons (this may indicate the presence of chalkbrood, a devastating disease). Wash the cocoons in a water/bleach mixture (1/4 cup bleach to 1 gallon water) and remove any that sink or have holes. Gently dry and store in a breathable wrap (like a nylon stocking), and store at 30-40 degrees and 50-60% humidity. Generally an attached unheated garage is suitable. See links at bottom for more info.
- Alternatively, tubes may be stored intact once nesting activity has completed, but handle delicately and be sure to set upright with mud-sealed ends at top. This will ensure that the eggs stay in contact with the food supply.
- Release bees in spring when temperatures have warmed appropriately, near their nesting site.
From the Xerces Society for Invertebrate Conservation: https://www.xerces.org/publications/books/managing-alternative-pollinators