What's eating my pelargonium 'wilhelm langguth'?

Pelargonium 'Wilhelm Langguth', a compact variegated zonal, is most threatened by the geranium bronze butterfly caterpillar boring into buds and stems. Aphids colonise new shoots, and vine weevil grubs can devastate container-grown plants. Whitefly is a secondary problem under glass or in sheltered positions.

Larvae tunnel into flower buds and stems, causing wilting and frass; affected shoots collapse without obvious external damage. Cut out and bin affected stems. Spray with spinosad or pyrethrin. Inspect buds weekly during summer and remove eggs by hand.

Dense colonies on tender growing tips distort leaves, transmit viruses, and produce honeydew that attracts sooty mould. Strong water spray to dislodge colonies; follow with insecticidal soap. Avoid high-nitrogen feeding which promotes soft growth aphids favour.

Grubs consume roots leading to sudden wilt and death of container plants; adults notch leaf edges at night. Apply Steinernema kraussei nematodes to moist compost in late summer/early autumn. Inspect root ball when repotting and remove any grubs by hand.

Adults and scale-like nymphs on leaf undersides cause yellowing and sticky deposits; populations explode in warm, still conditions. Yellow sticky traps; insecticidal soap spray repeated every five to seven days. Ensure good air circulation to slow population growth.