What's eating my achimenes grandiflora?

Achimenes grandiflora is a tuberous houseplant grown for its large magenta flowers. Its soft, succulent-textured stems attract aphids and spider mites. As an indoor plant that dies back to rhizomes in winter, stored rhizomes can attract fungus gnats in damp compost. Aphids are the single most common problem during the growing season.

Dense clusters of small green or black insects on new shoot tips and flower buds; buds distort or fail to open; sticky honeydew coats lower leaves. Knock off with a steady water stream or wipe away with a damp cloth. Apply insecticidal soap spray every 5–7 days until clear. Avoid excess nitrogen fertiliser, which promotes the lush growth aphids target.

Pale, stippled leaves losing colour; fine silk webbing on undersides and between stems; plants in hot, dry conditions deteriorate rapidly. Raise humidity with a pebble tray or by grouping plants. Spray insecticidal soap or neem oil thoroughly onto leaf undersides weekly for three to four weeks.

Adult flies hovering around pots; larvae in compost nibble fine roots, causing sudden wilting during active growth — especially likely in rich, moist potting mixes. Allow the top layer of compost to dry slightly between waterings. Apply a Bacillus thuringiensis israelensis (Bti) soil drench (e.g., Mosquito Bits) to kill larvae. Yellow sticky traps catch adults.