Several tents of 25-27mm catterpillars yellowy green to grey,black band on first segment black spots on all segments thereafter. Feeding on ash and privet
No interactions present.
These look like the Bird Cherry Ermine I found. Yponomeuta sp.
Bird cherry ermine http://ukmoths.org.uk/show.php?id=1287
You say it was on privet, but I think there is a cherry leaf in your photo. Can you take another look?
University of Edinburgh and Biodiversity Observatory (OU)
yes cherry was present but mixed through privet I also just found this http://biology.ie/article-single.php?a=132&PHPSESSID=47393835945bb7074e4... which might be of interest.
Thanks for the link, Foxy. There are an awful lot of species in this genus. A list at http://en.wikipedia.org/wiki/Yponomeuta
Lat/Lng: 52.6, -7.9
OS grid ref: SF0617