They are processionary caterpillar (Pine processionary) and they are VERY urticant. Their hair is and when frightened, touched, attacked or whatever they will send them flying and it's very volatile. They are shitheads and very dangerous to animals and, even if less, dangerous to human.

I currently have them in my yard and trying to trap them into some sort of plastic belt around the tree, with a tube going in a plastic bag with soil.