Answer: Insects are relatively indiscriminate in their feeding habits and simply do not target only the tips of the leaves of a plant. Deer will browse on almost any plant, as will rabbits. I suspect the culprits are deer. You can try spraying the foliage with Deer-Away (a repellant available in most garden centers), or with a homemade hot pepper spray to discourage deer from feasting in your garden.
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