Friday, November 27, 2015

Fall Mason Bee Care

Our little orchard was planted several years ago, but we'd weren't getting the yields we were hoping for.  Some trees had lots of blossoms, but little or no fruit.  Although we sometimes see honeybees and several species of bumblebees, we thought we should try some additional types of pollinators.

 Mason Bee, also called  an Orchard Bee or Blue Orchard Bees (BOBs)
I had heard of mason bees (also called orchard bees) several years ago.  Unlike honeybees they don't live in a hive and they don't produce honey, but they are excellent pollinators, especially of early blooming fruit and berry blossoms,  They live singly and the female usually lays her eggs in holes made by other insects or birds. In the past I had tried to encourage them by hanging up some blocks of wood drilled with holes. I saw evidence of some of the holes capped with mud, but the results were rather underwhelming.  I saw an advertisement for a free class about Mason Bees being offered at a local garden center and decided to attend.  It was there that I learned updated information about Mason bees and the reason why my previous efforts to propagate them had been unsuccessful.

Do NOT Hang Mason Bee Nesting Blocks Like This:

Wrong Mason Bee Nesting Block

Mason Bee Nesting Boxes with Trays

I found out that I had unwittingly created a death trap for the mason bees by not using either disposable straws or canes that would be used only once or better yet, by using trays that could be cleaned each fall and re-used.  Mason bees are susceptible to diseases and parasites which build up in nesting sites that are reused without being cleaned and will eventually kill the bees.  After attending the class, I ordered some nesting trays from Crown Bees and we set it up last spring near our orchard.

Crown Bees BeeWorks Chalet with Bees


We also built a nesting box and some trays with a design my husband and I created.   More about that later.  Fortunately it appeared that we had some success with several nesting holes plugged with mud, so last month it was time to see what we had.

Fall Orchard Bee Nesting Box Maintenance



Mason Bee Nesting Tray holes capped with mud

I spread out some paper on a workbench in the garage, but before I even opened the trays, the slightly warmer temperature inside the garage awakened several squatters like the one in the photo below. I set the trays out in the sun for a few minutes - just long enough to wake up the rest of the hornets/wasps so I could evict them by shaking them out. So the lesson learned here is to proceed with caution when opening the trays since you never know what might be inside.


A hornet or wasp emerges from a mason bee nesting tray

I started with the trays we purchased from Crown Bees and found a surprise.  Although the end of the hole was sealed with what appeared to be mud, the cocoons inside appear to be leaf-cutter bees, not mason bees.


Leaf cutter bee cocooons?

From the information I gathered about leaf-cutter bees, I thought they sealed their nesting holes with leaves and these looked to be sealed with mud.  I am by no means an expert, so will need to consult about what kind of cocoons these are with those who know more.

Scraping the Mason Bee Nesting Tray Grooves

The cocoons are easily removed without damaging them bygently using a screwdriver or small chisel.  Note that the channels in the tray need to be scraped and cleaned of all debris. Although most of this is mud and poop from the bee larvae, some of it can harbor disease, parasites like pollen mites and mold spores.  After using the chisel, I used a round file to clean out even more and then soaked the trays in a bucket filled with water with 5% bleach.  Next I opened one of the nesting trays that we made.

Mason Bee Cocoons in Nesting Tray

I was very happy to see a two grooves in this tray filled with what looks like mostly healthy mason bee cocoons.  Next I opened the nesting canes that were included with our Crown Bee Mason Kit   They were the first nesting holes that were filled so seemed to be preferred by the bees.


Canes with Mason Bee Larvae
The first cane revealed a few seemingly healthy  mason bee cocoons.

Mason Bee Cocoon with Pollen Mites
One of the canes did have a cocoon that appeared to be unhealthy.  My guess is that it has been infested and killed by pollen mites.  Note the yellow on the cocoon that is yellowish brown instead of dark brown and the shape that is round instead of cylindrical.

Candling a Mason Bee Cocoon
After brushing off as much debris as possible, I candled each cocoon quickly with a flashlight.  From what I've learned from my research, the photo I took above is what a mason bee larva should look like inside its cocoon.  What I was looking for was evidence of parasitic wasps which would have appeared as multiple tiny insects instead of one large one.  If the cocoon was full of parasitic wasps I would have destroyed it to prevent them from hatching next spring to infest more cocoons. This cocoon could still be a parasitic cuckoo bee, but at least I'm sure it isn't full of wasps.


Rinsing the Mason Bee cocoons
The next step is to rinse the cocoons with cool water to remove any remaining debris that might harbor parasites and disease.

Mason Bee cocoons drying

Next I placed the cleaned and rinsed cocoons on a paper towel to dry.  In addition to drying the cocoons before storing over the winter, the white paper towels also provide a good background for spotting any remaining dust mites or other parasites.

Mason Bee cocoons in a HumidiBee container

After the cocoons dried, they were ready to be placed in a Crown Bees HumidiBee container to spend the winter hibernating in my garage refrigerator.


Crown Bees Mason Bee Accessories Humidifier Storage Container, Humidibee

Next spring when it is time to put the cocoons back outside, I'll post an update.

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