Winter Questions, Answers and Observations

When do mason bees stop flying in the summer?


I picked up some mason bees from you in March. I am worried that they have all died or something. We put the box up on the back fence, shortly after we received it from you. It took a few weeks, but we eventually saw some bees flying about, and returning to their nesting box. This continued for a few weeks, and 22 of the holes have been plugged with mud.

Unfortunately, there has been no activity for the past six weeks or so. There are no bees to be seen flying around, nor going in and out of the nest box. The 22 plugged holes are still plugged, and again, there is no apparent activity. I did find one dead bee sitting at the edge of the bee house, in which I placed my nest box. I also found a hornet(?) building a nest inside the house, above the nest box. I killed the single hornet and removed the nest, which had only just begun. I have no idea if the hornet killed the mason bees or not.

My father-in-law also took home a nest box, and he has had even less activity than me, as he has only 10 plugged holes, and he rarely saw any activity at all, and none in the last several weeks.

Are there eggs inside the plugged tubes? Which will hatch next year? Or have we failed in our attempt?


I’m happy to report, that everything that you have described was supposed to happen. Bees emerge and forage between 4 to 8 weeks and then die. Inside the tubes are the eggs that are busily developing into new adults for next year. Your tube holds an average five bees. If you multiply that by the tubes you have filled…that equals quite a few bees for next year. Congratulations!

Bee and nest requirements


We received a mason bee kit last year and they were busy bees. Approximately 75 percent of the nests were occupied. What happens next year? We are interested in purchasing mason bees; how many do we require, what sex and quantities?


Sounds like you had a successful year last year. You can calculate the number of bees by multiplying the number of nests filled by 5. I would suggest not getting any more bees, unless you have a large orchard that you need to pollinate.

Cleaning the nest and bees


We love those little bees. Started last year with one colony or family and had the penthouse all full. Now we just bought another one for this year to fill.

The question we have is: How exactly does one clean the nests out in the fall, or whenever it is the time to do it? What is the procedure? Can one rinse the cocoons, if that is what they are called?

Thanks for the answer.


Yes, the fall is the ideal time to wash your cocoons. Cocoons can be washed and nesting trays can be cleaned ready for spring. The washing process uses cold running water. Use a mild bleach solution for the last rinse. A good description of the washing process is included in my book POLLINATION WITH MASON BEES and it is shown on my DVD.

2 replies on “Winter Questions, Answers and Observations

  • Rob Braide

    Hi there.
    I live north of Montreal. Which of the breeds do you suggest and do you also sell the cardboard tubes? I have a house that was not populated last year (I did no know about obtaining cocoons) and I need to replace some of the tubes. Thanks and happy new year.

    • Andrew Frizzell

      hi Rob,

      We mostly deal in Osmia Lignaria, also called Mason Bees or Blue Orchard Bees. They are pretty durable and adapt well to most environments. They have a reproduction rate around six to one or better, and will survive shipping, even across the country. And yes, we sell cardboard tubes. they are more difficult to clean and not reuseable, but much cheaper to send than wood or solid corn molded nests. If you decide to order bees, keep an eye on the timing, as you’ll need to catch your important pollen producers near the beginning of their bloom, so the emerging bees don’t miss out.


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