What's eating my calathea loeseneri (brazilian star)?

Spider mites and mealybugs are the chief threats to Brazilian Star Calathea indoors. Keep humidity high — dry air is the number-one trigger for spider mite outbreaks. Inspect leaf undersides and stem joints regularly and isolate any infested plant immediately to protect nearby tropicals.

Fine webbing on leaf undersides; leaves develop pale, stippled or bronze-streaked patches and may curl. Raise humidity with a pebble tray or humidifier. Wipe leaves with a damp cloth, then treat with neem oil or insecticidal soap spray every 5–7 days for 3 weeks.

White cottony clusters in leaf axils and along midribs; sticky honeydew causes sooty mould. Dab individual clusters with 70% isopropyl alcohol on a cotton swab. Follow up with diluted neem oil spray weekly until clear.

Adult gnats are a nuisance; larvae feed on fine roots in wet compost, causing wilting and slow growth. Allow the top 2 in (5 cm) of soil to dry between waterings. Use yellow sticky traps for adults; apply Bacillus thuringiensis var. israelensis (Bti) drench for larvae.