Insect Pollination: The Bees are Out Full Force

On my walks on May 2 & 3, one of the things that was hard to miss was the enormous amount of pollinator activity. I did not see any Apis spp. However, I did see a remarkably wide range of solitary bees, some syrphid flies, a single Bombus sp. queen, and of course the Bombylius major I posted about on Saturday. I also saw a single Pieris rapae (cabbage white butterfly) in the cemetery.

I am not able to identify all of the species that I have seen, but I took a number of photographs. It took a great deal of effort to get these shots. It's at times like this that I daydream about being able to buy a telephoto lens. How much easier it would be to take photos of pollinators if I didn't have to get my camera within a few inches of them!

Bombus sp. queen on Trillium grandiflorum

This Bombus sp queen was relatively easy to photograph, as she was rather sluggish. I discovered her pollinating some barely opened Trillium grandiflorum. She was so sluggish, in fact, that I actually managed to catch her in flight (shown below). She appeared to be focusing on the retrieval of nectar during the period I was observing her (note her empty pollen baskets).

Bombus queen in flight, just leaving Trillium grandiflorum after collecting nectar

This Bombus queen, however, was the only bee I didn't have to fight to get photos of this weekend. The rest were considerably faster and shyer.

One individual on whom I at least have a reasonably positive I.D. is this solitary bee visiting Scilla siberica; I believe this to be Andrena barbilabris.

Andrena barbilabris (?) on Scilla siberica

Another individual whom I believe I have identified reasonably reliably is this solitary bee, who I believe is Halictus ligatus, shown here visiting Tussilago farfara:

Halictus ligatus (?) on Tussilago farfara

There are a few more species I managed to photograph as well, but which I have been unable to identify as yet.

Unidentified solitary bee on T. farfara

Unidentified solitary bee on E. americanum

Unidentified solitary bee on S. siberica

There were many more than I managed to photograph over the weekend; I counted at least eight visibly distinct species of solitary bee pollinating the T. farfara, and there may well have been more depending on how visible and obvious the distinguishing characteristics of the species are; without a microscope and a specimen, it can be very difficult to judge. At any rate, the solitary bees especially were numerous and varied.

Insects are Harsh: Large Bee-Fly - Bombylius major - Grand bombyle

It was remarkably nice out today, so I decided to head out to the mountain with my camera to enjoy the weather and to see if the insects had started to wake up. They certainly have! In the various places where the spring ephemerals were in bloom, virtually no flower sat untouched for more than a few moments while I was observing. The pollinators are out in full force. I didn't see any Bombus spp or Apis spp, though. Just a variety of solitary bees, some Syrphid flies, a single Pieris rapae (cabbage white butterfly), and of course a large bee-fly.

The large bee-fly is a member of the Bombyliidae (bee flies) family, a group of bee flies (Order Diptera). Though they are flies, they are bee mimics. Mimicry generally is selected for when the mimicry is of a species to which predators are either indifferent or avoidant.

Unfortunately, the Bombylius major individual I spotted today pollinating T. farfara in the Notre-Dame-des-Neiges cemetery refused to hold still. It's quite tricky to locate an individual, pursue it until it lands, orient the camera in close without scaring the insect away, focus correctly, then take the photo. So, I have only the one photo, which is not great.

B. major pollinating T. farfara

In any case, B. major is a great example of the harshness of nature. B. major is a parasitoid of ground-nesting insects [1] (particularly solitary bees of the genus Andrena) [2]. The major difference between a parasitoid and a parasite is the outcome for the host. A parasite may reduce the fitness and competitiveness of the host, but doesn't assure its death or inability to reproduce; a parasitoid will eventually either sterilize or kill its host.

So B. major's basic method is to seek out ground nests (eg those of Andrena spp.) and deposit their eggs or larvae nearby so that they can crawl into the nest. The larvae then will attach themselves to the Andrena young, feed off them, and eventually kill them. Failing this, B. major will deposit the larvae on flowers that Andrena queens might visit, so that the larvae might be carried off into the nests. [3]

I witnessed a huge number of solitary bees visiting T. farfara today, so this B. major individual will have no shortage of potential hosts for its young.

Harsh.

Bonus photo of S. siberica, just to have something pretty to look at in this post:

Scilla siberica

Leafcutter bee - Megachile - Mégachile

This morning has been quite exciting for bees. We've confirmed that there are at least two bees in the B. impatiens hive (no photographs yet), and I've discovered that my bee solitary bee houses are being put to use.

I can confirm only that it's a leafcutter bee (fr: mégachile), genus Megachile. Unfortunately, I'm not able to pinpoint the exact species any more precisely, as I'm not a specialist in the leafcutter bees. Nevertheless, I can provide a photograph of a nest cell, and of the leafcutter bee. Enjoy!

 

 

Occupied Megachile nest cell, with distinctive cut leaves

As I understand it leafcutter bees favour the leaves from roses or lilacs for their nest cells. I think that the leaves here must have come from the lilac tree, which is within six feet of this nest cell (there are no roses nearby).

Megachile - leafcutter bee on mustard flower

I was very pleased to get such a clear photo of this bee. She's got the distinctive colour and stripe pattern of a leafcutter bee, as well as the distinctive outward resting position of the wings. Unfortunately I don't know encough about leafcutter bees to be able to identify what species she is. I don't know if this is the same one who built the nest cell photographed above, but I do know it's the same genus of bee, at least.

It's a beautiful day to be out in the garden.