If you have caterpillars eating them, you should be able to see lots of caterpillar poop on the ground under the tree. Poop looks like small black beads.

Looks like Oak Treehoppers. They are very colorful. http://bugguide.net/node/view/538 Here is a link that might be useful: Oak Tree Hoppers

I have officially geeked out about this plant. I love Lacy Phacelia. Its my new favorite rose companion. It's pretty isn't it? And it's already attracted so many hoverflies that they aren't just eating aphids...they are making babies and the larvae are eating aphids far away on other plants that aren't around the Lacy Phacelia! Diane and Natasha here's a photo showing the Lacy Phacelia in pots, but you can see that Corsican mint I was talking about in the background around the border of the pots. It's a groundcover like pennyroyal, but it likes part to full shade. I have it in pots around my berries. I also have a little "lawn" of it in the front yard near the shade of a redwood. So when it starts to grow too far out from the edge of the pots I just divide it and put it in the "lawn." Side note, that onion about to flower on the left came from food scraps of store bought organic green onions that I planted. How cool is that?

Lily, Every grub knows that sepals tickle the roof of their mouths, then the sepals get stuck in their throats going down, so they leave them alone. Grubs know the heart of the bud is the best part. After the heart is all gone, the sated grub will snuggle up inside the nest made by the sepals, and sleep off the feast, cradled in safety from predators by a sepal barricade, and that's an entomological fact I just made up! Moses