Late February, early March is the time the Mason Bees will start to be active.

There are natural nesting places in the landscape but for the purposes of this writing, I am going to assume we are buying or building a suitable nest, thereby becoming mason bee farmers or managers.  Mason bee farming is important as these small beneficial insects are susceptible to mites and predators.  By managing we can guard against the collapse of native colonies when mites (as an example) overwhelm them.  We can ensure that we have enough mason bees present for pollinating our crops and fruit trees.

The bees are most active when daytime temperatures are 14 degrees.  They may begin stirring around the time the Pieris are in bloom.  That may be a bit early for our area.  It would be better if they were around when the fruit trees are blooming.  We can manage their emergence to some extent by keeping them as cool as possible until we are ready for them.

The small bees emerge from their cocoons.  Males first, then about two days later the females.  Then the females go to work pollinating flowers and gathering nectar.

They are active from February to May depending on the weather conditions

  • the female muds up the back door of the tube
  • goes about her business pollinating and bringing nectar back to the tube
  • when she has enough nectar to feed the larva to cocoon stage, she deposits an egg on the nectar
  • muds up a wall so all the kids have their own bedroom
  • repeats until the tube is full
  • the first eggs will become female.  The last two (closest to the front of the tube) will be male as they emerge first.

Life Cycle

  • February to May – emerge from cocoon, gather nectar, lay eggs
  • May to June – eggs develop into larva
  • July – larva develops into cocoon
  • August – develops into a mature bee.  Usually by late September the development is complete
  • October through February – remain dormant in their cocoons.


Soon after the female emerges, she will begin looking for a suitable nest.

There are lots of materials suitable.  Wood is best in my opinion and readily available.  The holes drilled in the wood should be 7.5 mm in diameter and about 5 – 6″ in length.  Nesting tubes must be removable so that the nest and the cocoons can be cleaned.  You can make your own tubes.  Please research both nest materials and making your own nesting tubes for more information.  I use the cardboard tubes purchased for this purpose.  I find they are satisfactorily strong and easy to handle for harvesting and cleaning cocoons.

Mason bees are not apartment dwellers.  Each female prefers her own nesting site.  More small houses with several cardboard tubes each will encourage more females to work for you.  I did use a larger nesting box last year.  It did work but not as well as it should, I guess.  Totally my fault.  I did not colour the box and it was too large for one bee.  This year I will try painting the box into four different areas to encourage more bees into this large space.  I did harvest enough bees to set up several other boxes in other areas though.

  • Houses should have an overhang for protection from rain.  The bees like to have the entrance hole shaded so they can see any predators.  I imagine that is the reason anyway.
  • Preferred size of hole is 7.5 mm.
  • Tube depth of 5 or 6 inches will ensure a better balance of female to male population.
  • Decorating the front of a nest makes it easier for the bee to find their own nest.  Yellow, mauve, pink and blue are good colours for marking.  Simple designs are best.  Too complicated a design will confuse the bee and will not work any better than zero markings.


  • Place the nest facing east about 5′ above ground.  The bees will get the benefit of morning sun to warm up.  My nest last year faced southeast but was under the overhang of a shed so it got some shade from the hot summer sun.
  • This probably goes without saying, but the nest should be placed in close proximity to fruit trees or plants you want pollinated.  The bee will not have to go as far to deposit her nectar so more pollinating will be done.
  • She will need a source of water to make mud for her nesting tubes.  This is usually not a problem in our location.  At least for the months these guys are active.

Predators and Pests

  • Mites are a problem.  There is a lot of information about them in books and on the internet.  The mites hitch a ride and can become so numerous the bee cannot fly.  The mites can be washed off when the bees are still in the cocoon.  Please refer to the article I wrote last fall on cleaning cocoons and storing for the winter.
  • Parasitic wasps will attack the nesting tubes.  Parasitic wasps are usually active after the mason bees are done for the season.  If you notice parasitic wasp activity, drape a finely meshed bag over the nest.  This allows air to flow to the nest and keep out the wasps.
  • Ants can be a problem.  I have no experience with this so I hesitate to make recommendations.
  • Other.  There are a host of beetles, earwigs, birds which can be problematic.  i did not notice any of these problems last year.  Perhaps having the nest off the ground helps.  I understand that woodpeckers can get at the nests  Again, we have woodpeckers and didn’t have any problem with them.  Then again, we also have lots of trees around to keep them otherwise occupied.

Putting your harvested cocoons out

OK.  Let’s say we have got a year under our belt.  We have successfully harvested, cleaned and stored the cocoons over winter.

  • The weather conditions need to be right.  A few dry warm days in a row are ideal.
  • The hatching container must have a hole in both ends.  A small one for air flow and a slightly larger one for the bees to emerge from.  A few things will work.  A small cardboard box from a bottle of children’s Tylenol for example.  Important to remember, you need ventilation and an exit hole.
  • The container needs to be placed in close proximity to the nest you would like used.  We duct taped the box right to the nest last year.  The cocoons I bring in for sale are housed in a small cardboard box.
  • Luck.  No, not really.  The definition of luck is success or failure apparently brought by chance rather than through one’s own actions.  We have put effort into managing our Mason Bees and should have a successful season.

Happy Gardening!

Photo By USGS Bee Inventory and Monitoring Lab from Beltsville, Maryland, USA – ,F, MD, back_2015-11-20-21.40, Public Domain