Hundreds of (small-size) wasps are buzzing around in my weeping willow. On the stem and the branches there is busy traffic of wasps, and flies of all sizes, and fat blackflies. The leaves of the shrub under the tree or coloured black. So probably, flies and wasps are feeding on excreet/fungus from the blackflies. The remarkable thing is that the grass under the tree is literally covered with wasp corpses, and even more that these corpses are missing the hind tip of their abdomen, which is empty. Are they killed/poisoned, and then eaten, or are they being consumed from within? What is happening?
Cold nights will finiah them all off soon, but the black grenlfy might well persist and be a source of food again next year.