Yellowjackets are lousy pollinators. From a gardening point of view they are pests. They scavenge and steal and eat whatever they find and sometimes destroy. In this particular case, I have caught one munching on the stem. The wasp has bitten into it and probably munched on the sap. It definitively was not just cooling off its heels in the shade, her mandibles were moving and she took her time on that spot.
What the ones on the leaves were doing I have no idea, but I never saw one even near the blossoms.
© Charly, all rights reserved. Click for full size.
© Charly, all rights reserved. Click for full size.
© Charly, all rights reserved. Click for full size.
Thieves? No!
The Yellow Jackets are doing their carpentry. They are obtaining building material which they will take home to build their nests. Did you ever wonder where the paper originates for your wasps, hornets or yellow jackets?
Last year a family of yellow jackets nearly stripped the new growth on a lilac bush in my yard. This year I had only a single blossom to show for their activity.
@spitzmutt that did not occur to me. I see often yellow jackets to gnaw on dry wood to make their paper, but never fresh plant material as well. There is plenty of old dry wood in my garden for them, so they do not in fact need the fresh material.
Still, they are thieving resources from the plant and damaging it, the yellow bar stuards.
They may be thieves, but they look pretty against that fuzzy green.