[Seattleite]

Where did my bees go?

I started the season with 131 females (large) and 161 males (small).

We had a cold, wet, prolonged spring in Seattle, and the bees hatched two weeks later than they did last year. The cherry blossoms were long gone and the apples were half-finished by the time the bees emerged. I did see some males here and there over the course of a month, but I still didn't see any females until the weather was over 60 degrees for two days in a row.

When I peer into the tubes now (April 26th) with a bright flashlight, I'm counting 51 nesting females. There are maybe 20 females that haven't emerged yet.

Where on earth did sixty female bees go?


I've got four different style houses out, with a total of 182 tubes. The houses are located on the southern wall of a house in the city, with lots of flowering plants and trees in the neighborhood.

 

[Seattleite]

Just to follow up with more information . . .

I've learned that loose-cocoon management results in very high dispersal rates of females - few stay to nest. Letting the bees chew their way out of closed tubes in their natural state results in nearly 90% of females staying to nest.

There's a huge trade off between carefully managing individual cocoons (inspecting, cleaning, removing parasites etc.) and growing your population at a faster rate.

Perhaps the best approach for growing a healthy population is to maintain a portion of your bees in loose cocoons, and a portion as whole tubes. You wouldn't have perfect control over parasites, but it might be middle ground.

 

[Omie]

Seattle, what method do you use for cleaning and storing your cocoons?

 

[BorderBee]

Hi Seattleite,

I can't say I've had this same experience... This is only my second season with Mason Bee's. But when I started last year I had 10 loose cocoons that I purchased from a local keeper. There were about 4 females from what I could tell and all 4 stayed and worked on the tubes for the season.

At the end of the season I used the sand method to clean my cocoons and the population had grown to 45 cocoons, nearest I could tell 16 females. Again this spring they were in a small cardboard box in front of my tubes and hatched over about a 3-4 week period with a 100% hatch rate. I do regular checks to see how many tubes are being actively visited by females and while it's not exact believe I had 16 females working for a good portion of this year, still 2-3 alive from what I can tell right now, getting late in the season.

Anyways they have filled 29 tubes and counting and best guess right now is that the population growth rate should be about 4-5 times over again. I wonder if you are just in an area that has a high number of suitable nest locations? Or if something else happened to your population? Pesticides, other nasty chemicals, etc.?

 

[Seattleite]

Omie: I cleaned cocoons in three batches, one with the bleach method, one with Gord Hutching's sand method, and one with a miticide wash from Pasquale G in BC.

I keep the bee cocoons in plastic containers in the vegetable drawer in the fridge from late October through mid-March. Once a month I open the containers and wave some fresh air in. I've done it for three years, and it seems to work fine, with very low over-winter mortality.

I have four houses/condos of different design, and three of them have emergence-type containers. Beediverse uses an orange plastic prescription vial; Pollinator Paradise sent a small stiff cardboard box with a hole in it, and Pasquale's houses come with custom-fit wood drawers with a hole in them. So in all cases, a quantity of loose bee cocoons were set out in an emergence container with a single hole cut into it. I set them out in two batches; one in early March and one in late March. About once a week I picked through the cocoons and removed the empties. The four houses are all located on the south wall of my house, within about ten feet of each other, and each gets about six hours of full sunshine.

Horticulturally, last year the bees emerged when the cherries were starting to bloom, so they had several weeks of cherries and apples nearby (residential city neighborhood) to feed on. This year the bees emerged three weeks later, when all of the cherries and most of the apples were finished blooming. There are still lots of garden flowers and other blooming shrubs in the neighborhood, but perhaps the lack of cherries and apples had an impact.

 

[Seattleite]

As a followup, I did some further research on the subject and found that dispersal rates (when the females abandon the nest and fly off elsewhere) are much higher when using a loose cocoon management system, almost 90%.

Conversely, when bees are allowed to chew their way out of intact original tubes, more bees stay to nest in the hatching location., more like 50%.

Loose cocoon management has a lot of benefits of course, especially parasite control. If your goal is increasing population though, a combination of loose cocoons and whole intact wood blocks might be the way to go.

 

[woodinvilledave]

I am a commercial mason bee producer, and have developed a web site that is designed two help gardeners and orchards succeed. (http://crownbees.com) You should find most of your questions answered within the FAQ section.

If I can weigh in on a couple of points.

You really don't need to clean cocoons unless you find chalkbrood. Pollen mites exist in moist/humid states. If you harvest your cocoons, that's adequate. As you seperate out the cocoons, the amount of pollen mites leftover on the cocoons is miniscule. With the first forage flight, the mason bee will be picking up mites anyway. it's just part of nature.

The danger is when you don't harvest your cocoons (for example in a drilled block of wood). The emerging mason bees have to exit through the mite pockets and in many cases are unable to fly. When the hole is used again, there ia now an abundance of mites which will win in the "battle for pollen". These holes typically wind up as "mason bee cemeteries."

If you find chalkbrood (look in my pests page) THIS IS A BIG ISSUE. Wash your cocoons with about a 5% bleach solution. In addition, wash the inside/outside of your mason bee house as well.

With regard to loose cocoon management vs. leaving them in the straws. Commercially, we are all heading towards loose cocoon. chalkbrood forces this issue. And... we're not having any dispersal as someone mentioned. As the newly emerged mason bees leave their emergance bin/straw, they turn and memorize the area they left. That's where they're going to head back to begin nesting.

We'd like to help you succeed. Ask me directly for assistance in the contact us section.

Thanks,
Dave Hunter, owner
Crown Bees