What's eating my greater knapweed?

Greater Knapweed (Centaurea scabiosa) is a tough native wildflower that hosts a range of specialist insects, including knapweed gall flies and the knapweed plume moth whose larvae tunnel into flower heads. Aphids colonise stems, and rabbits graze young plants. Overall resilient, but gall larvae can visibly deform seed heads.

Hard swellings (galls) form inside seed heads, preventing seed set; may reduce plant vigour over time. No practical control needed in a garden; remove and dispose of affected heads if seed collection is the goal.

Sticky clusters on new stems and beneath leaves, leading to honeydew and sooty mold. Encourage natural predators like ladybirds; spray with insecticidal soap if colonies are heavy.

Larvae tunnel into stems and flower heads, causing wilting and distorted buds. Cut back affected stems below the entry hole; dispose of in the bin, not the compost heap.

Young basal rosettes and flower stems grazed, particularly on new transplants in spring. Wire mesh protection for young plants; established knapweed in meadow settings is less vulnerable.