Fall Care For Mason Bees
Excerpted from: Fall Care for Mason Bees
Mason bees are a group of bees in the Osmia genus. There are 140 species in North America.
They are solitary, meaning that they don't live in a colony with other bees. Instead, the male
and female mason bees live and work alone, except for mating. Mason bee females may nest
together in mason bee homes we provide them.
Mason bees do not require extensive maintenance like honey bees. You can simply buy or make a mason
bee home (lots of style options, but make sure you can take the whole home apart to access cocoons in the
fall, or use paper tube liners in drilled holes), mount it outside in late February/March, and wait for wild
mason bees to find it. They will get busy laying eggs in the home, and then it's your job to clean the home
in August-October, and store the cocoons over the winter to keep them safe.
For more information on Mason Bees, see:
Mason Bee Profile
When you put up a mason bee home, you are encouraging the bees to lay a bunch of eggs very close
together. In the wild, the bees would be forced to lay a few eggs over here in a hollow stem, and a few
over somewhere else.
With many nests together, it's easy for parasites to locate them and move from one nest tube to another.
Your whole mason bee home could become a breeding ground for parasitic wasps, pollen mites, fungi,
etc. over the winter (see photos below). So because we are setting up these unnatural situations, it's
important for us to be responsible and give the bees a hand, so we don't do more harm than good.
Open up your mason bee home or pull out and unravel the paper tube liners. (brown stuff that look like
mini-chocolate sprinkles is bee poop (frass), yellow/orange sticky stuff is pollen, light brown-reddish
stuff that moves slowly are pollen mites.)
If you have a tray/routed house design, scoop out cocoons gently using a chopstick or tool designed for
this purpose. Float the cocoons in a bowl of cool water.
Gently roll the cocoons with your fingers to clean off frass etc. You can also use an old toothbrush to
gently scrub the cocoons. Cocoons can stay in water for up to an hour, but I usually only soak for a few
minutes. Inspect cocoons for holes.
If they have a tiny hole in them, parasitic wasps have gotten in, and the bee is dead. Cocoons that sink
Scoop up cocoons and float in a bowl of 1L (4 cups) cool water and 1 tsp hydrogen peroxide or bleach.
Swirl the cocoons around and let soak for a few minutes. This kills off any fungi and bacteria on the
cocoons that could infect them later. Afterwards, disinfect the mason bee home by soaking in the
solution for 15 minutes.
Rinse the cocoons thoroughly. I do this in a sieve under cool running water.
Layer cocoons and crumpled up paper towel in a glass jar with many holes punched in the lid. The
cocoons want to be dry and have air circulation so mold doesn't develop. Put the container in the
fridge, or in an unheated garage or room. Monitor them for signs of mold. They want to be at about
60% humidity, and above freezing. Some say that fridges can be too dry for the cocoons. Try storing
cocoons in a few different locations you have available and compare their hatching rates-then you'll
know the best storage location for next year!
In the spring, when temperatures are about 55° F, and fruit trees are about 25% in bloom, bring
your cocoons outside and place them in an open container in the sunshine. The males emerge first,
and do not sting. The females emerge a few days or weeks later.
Plants had to solve a problem: they needed to find ways to spread their genetic material.
Flying pollinators were nature's solution. Nectar is made as a reward for pollinators.
Take this quick quiz and see how much you know about bees—our favorite essential pollinators
working around the world. This quiz is intended for fun, in a random-facts-can-be-cool kind of way.
Spring begins andhungry pollinators are on the wing, looking for food. From
the moment emerge in spring to the time that they hibernate or migrate in the fall, pollinators
need to eat.