Our walnuts are being ravaged by this pest. We tried a pesticide recommended by a geoponos (we're in Greece), but it was probably too late, and in any case we are trying to be as organic as possible. After some searching, I read that this is a larva of a beetle, which descends from the trees when it gets cold, and buries itself in the ground around it. Apparently they are fragile and can be destroyed by plowing around the tree. We'll try this, but in the meantime, has anybody else used any other methods to kill this thing? I gather it will also attack figs, mulberries, palms, and who knows what else.
Grateful for any further information!