Diptera: Cecidomyiidae - gall midge Contarinia jacobaeae Gall in Senecio erucifolius / Jacobaea erucifolia, Hoary ragwort Hosts: Jacobaea aquatica, erratica, erucifolia, paludosa, vulgaris; Senecio sylvaticus, vernalis, viscosus, vulgaris Base of flowerheads are swollen and +/- fleshy, sometimes also upper part of stems. Gregarious larva are yellowish-white or yellow with the ability to jump. Several generations, pupating in ground Similar: Sphenella marginata. Dipteran larvae, pupating in gall

Contarinia jacobaeae
Badbury Rings, Dorset. September 2018