Spinselmot or — I think — Willow Ermine (Yponomeuta rorellus). Until last night’s storm tore through most of the webs, the larvae of these black and white moths had engulfed whole trees, mostly willow, in the Rembrandt park and here, along the Sloterplas. I’ve seen pictures elsewhere of them engulfing nearby park benches and bicycles as well. I’d call these Stephen King caterpillars.
Irma has better pix and calls them “Cristo Moths.” It’s apt — the infected trees stand out like silver ghosts, covered from trunk to twig.