Saturday, August 6, 2011

Visit from The Great Black Wasps

Many wasps are flower visitors, and thus pollinators. Although most of these flower-visiting species are predators, capturing arthropod prey to feed their larvae, the adults seem to require a regular diet of nectar to satisfy their energy requirements.

Wasps in general don't have the multitude of branched hairs that make bees pollen magnets. But the frequency with which they visit flowers means they inevitably transfer some pollen as they go.

At the Evergreen Brick Works many wasps can be seen on a variety of wildflowers. Earlier I wrote about the Great Golden Digger Wasp (Sphex ichneumoneus) visiting Virginia Mountain Mint. That spectacular species was seen frequently two years ago, but last year it was rare. This year the Great Golden Digger Wasps are back, and they have been joined by a close relative, the Great Black Wasp (Sphex pensylvanicus).

Both of these are large, an inch or more in length. In the Kaufman Field Guide to Insects of North America, Eric Eaton refers to them as 'regal.' The Great Black is probably the larger of the two. And as a dozen or more of them come and go among the flower heads, they are definitely the most noticeable.

Great pollinator watching!

[Photo (c) D. Barr]

Thursday, August 4, 2011

Pollinator Drama on A Floral Stage

This is an interesting photo that I took of a four-way biological drama taking place on the flat stage of a Queen Anne's Lace flower head.

The most obvious player is the curved, black-and-yellow body of a potter wasp, one of the Eumeninae (Vespidae) and possibly Ancistrocerus albophaleratus. So obvious in fact that this insect is the thing that attracted my attention in the first place. These wasps are enthusiastic flower visitors, a habit that was the undoing of this particular individual.

But this one was strangely still. Usually they flit away once you get the camera lens too close. Actually the wasp you see here is now only a corpse. She was killed in the course of her visit to the flower in search of nectar.

It turns out that the killer is in the photo too. Just to the left of the wasp you should be able to make out the vertically oriented body of a Jagged Ambush Bug (Hemiptera, Phymata sp.). These consummate hunters spend most of their time on flowers too, their mottled black and greenish-white coloration serving as effective camouflage. When an unsuspecting pollinator ventures too close, the bug lashes out with powerful, raptorial forelegs and quickly dispatches its prey.

So the flower provides the stage for the story of life-and-death involving the bug and the wasp. But what of the fourth player in our little drama?

Perched on the thorax of the wasp you should just be able to make out a small fly. What role does this new character play in the drama? Hard to say. Could it she be a parasitic female that has come to lay her eggs on the wasp, hopeful she has found a good meal for her offspring? I don't know.

But I do know that an awful lot of biology goes on in the wildflowers that surround us each summer. Yet another excellent reason for preserving habitat for all of these species.

[Photo (c) D. Barr]

Wednesday, August 3, 2011

News Item: New Site for Citizen Scientists

Mother Earth News has just announced a new feature on their website - a meeting place for gardeners and an information hub for those interested in practicing citizen science.

This section of the site is powered by something called 'your garden show'. The gardening stuff is great, as there will be resources there for wildflower gardeners. But the access to citizen science projects is fantastic. It allows you to to participate in national and international science projects right in your own backyard.


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