More likely winter moth caterpillars. Yuck.

If you look at the uMass landscape message that Claire posts, look at the one for 9 May (on page 2 of the forum). That has winter moth info.

My daughter has been collecting them thinking they are inch worms. At first I was discouraging her. But then realized better to have them in her
bug house than snacking in my trees.

UMass suggests BT, a non-toxic bacteria, for treatment of these pests.

Since the caterpillars have to eat it for it to work, it is actually very narrowly targeted - specifically, it won't kill butterfly larva, even if some of it drifts onto them.

I've applied it using a hose-end sprayer, and although I can't reach the tops of my big maples, I can get it onto pretty much all the visible leaves, which has been pretty effective. My main problem with W.M.s has been on ornamental cherries, maples (which I don't especially care about) and on assorted smaller woody plants, like blueberries and roses.

Here is a link that might be useful: winter moth fact sheet

I believe they are winter moth caterpillars. I use BT once a week around this season, but I cannot reach huge oaks and maples. So I spray it almost all shrubs and perennials under the trees. BT works very good, but I cannot spray it when it is peak - the caterpillars fall like shower on you. Maybe I would like to try oil or tape next year...

Thanks for the replies. I'll have to leave it to the condo association. And be extra careful when sitting on my back deck.

This too shall pass...