What's eating my river water fern?

River Water Fern (Blechnum spicant) is most troubled by scale insects and mealybugs indoors. Spider mites can colonise fronds in dry air. Keep humidity high, inspect new growth regularly, and isolate any affected plant immediately to prevent spread to your collection.

Brown or tan waxy bumps on frond midribs and stems; fronds yellow and weaken as sap is drained. Scrape off visible scales with a soft toothbrush, then apply neem oil or insecticidal soap; repeat every 7–10 days for a month.

White cottony clusters in leaf axils and along rachises; sticky honeydew leads to sooty mould. Dab individual colonies with a cotton swab dipped in 70% isopropyl alcohol; follow up with neem oil spray weekly until clear.

Fine stippling on frond surfaces with faint webbing; fronds turn bronze or drop in heavy infestations. Raise humidity, rinse fronds with water, and apply insecticidal soap or neem oil; repeat every 5–7 days for three cycles.