Vine weevil
Adult beetles notch leaf edges at night, while their soil-dwelling grubs eat roots, often killing container plants before you notice.
Also known as: Black vine weevil, Otiorhynchus sulcatus
Symptoms and identification
Irregular notches chewed from leaf edges. Pot plants wilt and collapse even when watered; tipping them out reveals cream, C-shaped grubs with brown heads among the roots.
Causes
Flightless adult weevils, all female, lay eggs in the soil of pots and beds in summer. Container plants in soft potting mix are especially vulnerable.
Organic treatment
Water beneficial nematodes into moist compost in late summer and spring when soil is above 5 °C. Hand-pick adults at night.
Prevention
Inspect the roots of new plants, check plants with a torch at night for adults, and keep pots off the ground.
Chemical treatment (use with care)
Use a product labelled for vine weevil grubs on ornamental container plants, following the label.