The Day The Mason Bees Emerged

Mason bees emerging in spring

As interesting as it is to see mason bees surface after a winter dormant, I was hoping they would wait another week or two as there are virtually no flowers on our roof. Crocus have left us, currants, blueberries and gooseberries all look to be about a week or two away… in fact the only flowing plant on the roof is our massive rosemary. Oh well.

It was purely by chance that I checked the bees this afternoon and noticed a few plugs opened and bees at the entrance. As I’ve mentioned previously, last year we used store-bought bee houses along with bamboo tubes. Since the tubes were nearly impossible to open, I left them in the houses and just moved them to a safe, sheltered place on a north-facing balcony. As a result, the cocoons weren’t cleaned and the temperature control was left largely to nature.

What happened? Well, I was expecting that a lot of the tubes would not emerge at all. As I said, I hadn’t cleaned them, I hadn’t controlled the temperature, they weren’t perfectly shielded from rain through the summer… but I was pleasantly surprised. Emergence happened all at once with mason bee after mason bee peeking out of their tubes and taking short hops before settling on a south-facing surface presumably to warm up.

The major issue was something I predicted in an earlier post. While all of the bees looked fat and well-fed, there were some that were absolutely plagued with mites (see the photos in this post). Others, fortunately, seemed to be completely unaffected by mites, but those that were were covered by them.

Mason bee covered in mites
Mite-infested mason bee minutes after emerging from bamboo tubes. March 2020


Takeaway? This year’s cardboard and paper tube (Canadians can find cardboard tubes here) test is probably warranted given the situation with mites on my mason bees. Toward summer’s end I need to remove and open the mason bee tubes, remove the cocoons and clean them before storing them in the fridge (or other suitable location) until next spring. Hopefully, IF the bees choose to use the paper tubes, and IF the babies survive to form cocoons, and IF I remove and clean them properly we should have a healthy population come next spring.

Healthy mason bee
Healthy mason bee minutes after emerging. March 2020


Mason bee minutes after emerging
Mason bee minutes after emerging. March 2020

The Problem With Pollinators Part II – Good, Bad And The Nasty

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It’s the middle of April, so time for my second post on native pollinators. This year I again purchased a handful of mason bee cocoons to get a jump on pollinating until the bumblebee and honey bee populations can find the roof. I should mention that last year several of the tubes in my bee houses were filled and sealed by the mason bees introduced at that time. Unfortunately I didn’t properly take care of them over the winter, though I intend to do so this year if I’m given a second chance. For anyone else in a similar situation, here’s a handy guide to harvesting your mason bee cocoons at the end of the season:

The Good. As mentioned above, the cocoons we set out last year hatched (not all, but many of them) and were seen happily pollinating the flowers across our roof. After a few weeks I started to see a few of the tubes closed off with mud. All in all perhaps a dozen tubes were closed in this fashion.

The Bad. First, I noticed many small insects around one of my bee houses in particular, this being the one housing the leaf-cutter bee cocoons. They were almost certainly predatory wasps, and looked like this. Their presence might explain the very low hatch rate for the leaf-cutter cocoons that I’d purchased. Also, as mentioned above I didn’t properly harvest the mason bee cocoons, and instead left them outside over the winter. Fortunately for me, almost all of the plugged cocoons appear to have hatched this spring, and I’m seeing bees buzzing about the bee houses even though the newly purchased cocoons haven’t yet emerged.

The Ugly. While most of the bees I’ve seen up close this spring have looked healthy, I’ve encountered a couple that were absolutely INFESTED with mites. If you look at the photo at the top of this post, you’ll see 6 mites hitching a ride on the bee’s back. In one instance there must have been HUNDREDS of mites on the poor bee. As such, I will be absolutely sure to properly harvest the cocoons this year, and will at minimum continue to replace all tubes with new bamboo, and possibly replace the houses themselves.

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