How To Wash Mason Bees

Why

One of the joys and responsibilities of keeping mason bees in manufactured nests is taking the nests apart and washing the cocoons in preparation for their spring release. Unmanaged mason bees, wild bees in their natural setting, rarely reach the same levels of population density as do managed bees kept in human made nests. In nature there are cycles of population rise followed by collapse that we wish to avoid in managing mason bees.

Washing mason bee cocoons, when done correctly, not only aids the bees by helping to prevent losses due to pollen mite competition and wasp parasitism it is also an excellent way to be intimate and up close with this gentle and vital bee. Mason bees, like other bee species, are susceptible to a number of bacterial, fungal and bacterial diseases. Removing the cocoons from the nest will give you
a chance to clean it and cut down on the bee’s exposure to diseases.

Washing the cocoons is a great activity for children to engage in. Since the bees are dormant and wrapped up in a cocoon there is absolutely no danger of stings. And it teaches children to respect nature, not to fear it.

When

The best time to wash mason bee cocoons is between September and December. Usually by the end of August the bee pupa are in their adult form within the cocoon but have not yet fully matured. The bees are unlikely to prematurely emerge during this final stage of development and are also less affected by warm temperatures.

If you cannot wash the cocoons before January then it is much more important to keep the cocoons cool and to be even more gentle in handling them when you do. Washing them outside during cool weather in cold water helps to keep temperatures down while you handle the bees. Remember that bees are cold blooded and require heat, normally from the spring sun, to break winter dormancy.

If you do wash them inside after December do so quickly in cold-water to avoid rousing them from dormancy. Don’t let the lateness of the year deter you from washing them.

Tools

• Wash Basin with cold water
• A flat headed screwdriver, a curved carving knife or a BOB nest scraper
• A wire sieve
• Paper towels or clean dry cloth towels

How

How one gets at the cocoons is a matter of what kind of nest you have.

If you have the sort of nest that is comprised of holes drilled in blocks of wood and there is no mechanism for getting the cocoons out then you cannot wash them this year. Consider drilling the holes wider so that a paper or cardboard straw can be inserted. If you do this, be sure that the ends of the paper or cardboard don’t protrude as this will wick moisture out on a hot dry day and will draw moisture into the nest on rainy days.

Generally there are two kinds of nests that are designed to have the cocoons removed: the tray kind with cavities for the bees either routered out or formed in some way; and the straw or tube type. The bees don’t mind either one. The main difference between them is the cardboard or paper tubes are a one-use kind of cavity for the bees, whereas the tray type can be used multiple times. So it really is a personal choice to make.

If you have a tray nest pry it apart and gently lever the cocoons out of the routered cavity with a screwdriver or with a curved carving tool. You’ll see there are quite a lot of things in there. I usually use an old cookie sheet covered with a piece of light coloured paper to catch everything.

I put aside the nest to be scrubbed later in hot water and a bit of bleach.

With the tubes or straws some people will soak them in cold water to make it easier to unravel them. I personally make a small incision on one end with a very sharp knife and take the tubes a part while dry. I find this makes it easier to examine the contents of the tubes, which is at least half the fun.

What you will find inside a nest, aside from a fair amount of dried mud, is quite amazing. Early in autumn the Hairy Fingered pollen mite will be clearly visible crawling about. Later they will have mated and only the yellow/light orange eggs clustered around the bee cocoons are to be seen. Don’t confuse the orangey rust coloured dust with these; those are also pollen mites, just a much smaller
species.

Cells empty of cocoons can be seen. If the pollen mound that the female bee provisioned the cell with is still there it may be that a wasp parasitized the bee larva. If you poke around a bit you may find a somewhat c-shaped shriveled worm like carcass. This would be the bee larva. If the cocoon is there but no bee is inside, look for a hole where the adult wasp, once it developed and
pupated inside the cocoon, escaped.

~Brian