I planted a Elaeagnus x ebbingei hedge 2 years ago. It has always had these insects on it and I kept them at bay by individually washing the leaves. But now it is too big and is suffering badly! There are about 16 plants and all affected. Myrtles in between are fine. Leaves have yellow patches on upper side and grey/ black powder on underside. Insects also on underside. White waxy stringy deposits on tips of branches during summer.