|Unknown species of wasp on Achillea millefolium|
Another possible reason that wasps aren't such efficient pollinators of bees is that they don't (for the most part) rely solely on flowers for food. This individual actually may have inadvertently provided pollination services to the flower, but wasn't there collecting either nectar or pollen. She was dining on something else entirely:
|A wasp eating something - note the ball of wax-yellow stuff|
|Wasp eating something -- ball of stuff still unidentifiable|
A quick glance around the environs, however, provided the answer:
|Seems like a colour match for that wasp's meal|
I suppose one animal's rather grisly find is another's feast.
Anyway, wasps will seek out other sources of protein (often to feed their young), including other insects, whereas bees generally don't. This reduced reliance on flowers may make them less likely to do the systematic flower-by-flower collection that also makes bees such suitable pollinators for flowers.
Wasps are actually an excellent biological control agent, as many of them have preferred prey which are pest insects on crops. I encourage them in my own garden because they're so efficient at getting rid of unwanted insects.
These oft-maligned insects are actually pretty awesome -- as long as you don't swat them or approach their nests late in the season.