I too am wondering what the damage will be..and what they will look like as moths..can't seem to find a picture of the adult moth!
thanks~

....everybody photographs the caterpillars, but no one seems to come up with photos of the living moth.

- maybe you are just getting more observant!

Seriously, trees can stand a lot of foliage being eaten without suffering much permanent damage, but on the other hand increased infestations may be a sign that the tree's defences are weakened - stress can show up as color changes or changes in gases exuded, which can be detected by "pests" that want to eat them. If you've had a dry summer you might want to give the tree deep watering occasionally. One of my horticulture teachers whom I respect very much taught me that the majority of the time insect infestations are a response to over- or under-watering causing stress. He was talking about greenhouse plants but I think you can extrapolate to trees.

BTW scientists have found that a bean plant can lose 30% of its foliage (to skipper larvae) without reducing the yield of beans. I'm not bold enough to apply that to trees, but it makes you think!