What's eating my dwarf nasturtium?

Dwarf nasturtium (Tropaeolum minus) is notorious for attracting aphids — particularly the black bean aphid — which colonise stems and leaf undersides in huge numbers. Caterpillars (cabbage white, as nasturtiums are a Brassicales relative) eat leaves, and slugs target seedlings. Many gardeners plant nasturtiums deliberately as aphid trap crops.

Massive colonies coating stems and leaf undersides; leaves curl and yellow; honeydew everywhere; ants attend them. Squash by hand (nasturtiums are a trap crop — tolerate or remove infested plants to dispose of aphids en masse); spray insecticidal soap if control is needed on ornamental plants.

Irregular holes and scalloped leaf margins; pale green caterpillars found hiding on leaf undersides. Hand-pick eggs and caterpillars; apply Bt spray; cover with fine mesh if preventing damage is the priority.

Seedlings cut off at soil level; large holes in mature leaves; slime trails on foliage and soil. Use iron phosphate pellets; set beer traps; remove slugs by hand after dark; avoid overhead watering.