What's eating my button fern?

Button fern (Pellaea rotundifolia) is susceptible to spider mites in low humidity and to scale insects on its wiry stems. Mealybugs may colonize the dense leaf bases. Because button fern prefers drier conditions than most ferns, watering carefully reduces fungus gnat risk. Inspect the compact fronds regularly — pests can build up unseen in the dense growth.

Fine stippling and yellowing of the round, leathery leaflets; webbing between fronds in severe infestations; leaf drop. Wipe leaflets with a damp cloth; spray insecticidal soap or neem oil; increase ambient humidity slightly and repeat weekly.

Tiny brown or cream bumps on wiry stems and leaf undersides; weakened growth; sticky honeydew residue. Scrape scales off manually; apply horticultural oil spray; treat again in 2 weeks to catch newly hatched crawlers.

White cottony patches at stem joints near the crown; reduced vigor; honeydew and sooty mold if left unchecked. Swab visible colonies with rubbing alcohol; follow with neem oil spray; isolate from other plants and monitor weekly.