Thanks for all the responses! I =think= I have IDed them as some kind
of leafrollers. They're like little green caterpillars or inch worms,
a little longer than a grain of rice, and they roll themselves into
the new leaves with some kind of silk/web. Both of the little oaks
are heavily infested now, and the first one has only a few whole
leaves left; the leafrollers have also found the roses. I think I'm
going to have to try the BT.

Oh well, at least I don't have leaf-cutter ants like my mother-in-law
down in the Valley!