Q.OSTRICH FERN ASTILBE
Upstate NY, Zone 4, have four different Astilbes. One is problematic…the OSTRICH FERN ASTILBE. Something eats the flower heads and the leaves have holes, while my other Astilbes, Pink, Red and Purple are untroubled. Tried coffee grinds, tried loads of crushed eggshells, even slug bait to deter slugs and or snails. That didn’t work at all. Who is the culprit ? Could it be a bunny ? Could it be a skunk ? There are no deer, so for certain that isn’t it. Any suggestions before I give up and yank them all ?

Insects that feed on fern fronds include: sawfly and Lepidoptera larvae, cutworms, beetles, crickets and grasshoppers.
Treat the plants with Neem Oil.
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm