Help-Hornets!

[Toby Hemenway <hemenway@jeffnet.org>]

Believe it or not, this is not more filosifizin' but a request for
practical advice. Briefly: this year we are overrun by bald-faced hornets
that are eating nearly all my fruit before I can get to it, and I'm
wondering if this is just a short phase in the ecological development of my
evolving landscape, or if I should implement some strategy to bring the
hornets back into balance. I don't mind hornets, I just want some fruit.
  The long version (you knew there would be a long version, right?): We've
lived on this south-facing, summer-dry Oregon hillside, covered mostly with
doug fir and madrone, for 6 years. The fruit trees I planted  are just
beginning to bear (most are in young guilds), and suddenly this year,
billions of bald-faced or white-faced hornets have showed up (Vespula spp.;
not bees or wasps but true hornets). We've always had yellowjackets in
summer (which the hornets eat in a very gruesome display, plucking them
from the air, snapping off the wings, head, and abdomen, and munching the
protein-rich thorax while the legs still wriggle), and we've had hornet
nests nearby, but never any problem with them. But I can't even get to my
fruit; the hornets completely cover the peaches and figs (and we have lots
of figs!) with a writhing black mass as they devour them, even spending the
night on them, and have made harvesting grapes and plums a challenge as I
must gently sweep 2 to 5 hornets from each piece of fruit before picking
it. I'm hoping that the problem is simply that I've offered a new food
source that is still in fairly short supply (about 6 young stone-fruit
trees and 3 figs are bearing, with more trees to come) and thus there is a
temporary burst in population that will die down when natural predators and
controls ramp up to speed.
  Should I do anything or wait it out? Has anyone been through this before?
As more fruit comes on will this be less of a problem or will the hornets
continue to multiply-yikes!-in response to new food? What are hornets'
natural controls and can I take steps to encourage their presence? Why
isn't the planet waist deep in hornets? What's a nice permacultural,
ecological approach to this?