Ermine moth caterpillar nest?

Ermine moth caterpillar nest?

Observation - Ermine moth caterpillar nest?. Description: Nest of caterpillars on Bird-cherry. This is a relatively light year so far. Last year, the caterpillars more or less stripped the Bird-cherry bushes in the hedgerows. This doesn't seem to have done the trees much harm. I added photos 2 and 3 a coupl

"Nest" of caterpillars on Bird-cherry. This is a relatively light year so far. Last year, the caterpillars more or less stripped the Bird-cherry bushes in the hedgerows. This doesn't seem to have done the trees much harm.

I added photos 2 and 3 a couple of weeks later. If anything, the infestation is even greater this year.

Photo 4 (added 2.7.11) shows adult recently emerged from the mass of pupae on the tree.