Most larvae, both wild and domesticated, are now beginning to feed. The problem is that they align themselves to leaf buds rather randomly - some select early-opening buds, some select late buds, and some particularly dim ones select damaged or dead buds. Also, they occur on both early and late-leafing sallows. One domesticated larva is skin-changing, though three others haven't started to feed yet.
Here is a nice up-the-pettycoats view of Lot's Wife, taken in Wiltshire yesterday -