I saw something similar to what was in the above article at the Botanic Garden in Amsterdam on the18th May. Also cause by spindle ermine moth larvae (Yponomeuta cagnagella).
I am afraid my image just doesn't do the reality of the scene justice it had a very creepy look. The spindle was totally covered by the thick web which extended upwards, three floors to the roof and around the corner. In every crevice of decoration and under the window sills there were pupae, but there were still thousands of larvae still to pupate hanging from threads or still in nests. The larvae had totally stripped the tree of foliage and it looked dead, but I was talking to a gardener and he said in a month or so more leaves will grow back. He also said this tree is affected like this every year and they leave it to it's own devices, but a spindle in another part of the garden they treat.