What's eating my columnea linearis?

Columnea linearis, like other goldfish plant relatives, is most frequently attacked by mealybugs sheltering in its dense, hairy stem joints. Spider mites can also establish on the undersides of its soft leaves, especially in low humidity. Regular inspection of leaf axils and prompt isolation of affected stems are the best defences.

Fluffy white wax masses tucked into stem joints and leaf bases; honeydew and sooty mould on foliage; overall vigour decline and reduced flowering. Treat with isopropyl alcohol on a cotton swab for localised patches. Apply neem oil or insecticidal soap spray, paying close attention to all axils. Repeat every 7–10 days for a minimum of three treatments.

Pale stippling and a dusty, bronzed look to leaves; fine silk webbing underneath; premature leaf drop in heavy infestations. Increase humidity by grouping plants or using a pebble tray. Spray undersides thoroughly with insecticidal soap or dilute neem oil. Remove and dispose of badly affected stems.

Tiny dark flies hovering around the compost; larvae in the topsoil feed on fine roots, causing wilting and poor growth — especially problematic in moist, peaty mixes. Allow the top 2 cm of compost to dry between waterings. Apply a Bacillus thuringiensis israelensis (Bti) drench such as Gnatrol or Mosquito Bits solution to the soil to kill larvae. Yellow sticky traps catch adults.