Answer: There are a host of beetles and their larvae that find willow leaves inviting. Without being able to inspect the plant, I can't suggest a control. If caterpillars are evident, Dipel or Thuricide will control them. If beetles are on the leaves, you may be able to knock them off with a strong stream of water or to use a Neem Oil based insecticide labeled for ornamental use against beetles. Good luck with your pussywillow.
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