What's eating my intermediate polypody?

Intermediate Polypody (Polypodium interjectum) is a European native occasionally kept as a cool houseplant. Indoors it is most likely to suffer from spider mites in dry heated rooms and scale insects on its rhizomes. Mealybugs are a secondary risk. It is naturally robust; overwatering and resulting root rot pose a greater risk than most pests.

Fine pale speckling on fronds; thin webbing under leaflets; fronds lose colour and may drop Boost humidity, shower fronds to dislodge mites, and spray with insecticidal soap or neem oil weekly

Hard brown raised spots on rhizomes and frond undersides; honeydew and sooty deposits Manually remove with a damp cloth or soft brush; treat with horticultural oil or insecticidal soap fortnightly

White waxy tufts at rhizome joints; yellowing and sticky fronds Dab colonies with isopropyl alcohol; apply neem oil spray every 7–10 days for a month