Answer: Based on your description I am not certain what you have found, because I can't think of a typical astilbe pest that would leave eggs in the foliage. You might have seen aphids clustering on the newest tender growth. They are small, soft bodied sucking insects and can be knocked off with a strong spray from the garden hose or sprayed with insecticidal soap according to the label instructions. If on the other hand you really did find some sort of eggs, probably the best thing to do would be to remove them.
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