Sphenella marginata

One of many flies in this family with distinctive patterning on the wings.

Galls are formed in the flowers of Ragwort, causing the flower heads to swell at the base, with enlarged bracts. White larva or brown puparium inside. 

Other Tephritid or Anthomyiid flies are found on Ragwort, but do not cause galls. A gall-midge, Contarinia jacobaeae, causes similar galls; the larvae live communally between the achemes and are small, cream or pale-orange, and jump.  

Adult Gall

If you are recording the gall, provide a photograph of the larva inside the gall. 

Various well vegetated habitats where the larval host plants are present.

June to September.

The larvae of this fly mine flowers of Ragworts and Groundsels. The flower head widens at is base, resulting in a cone shape; the bracts are widened. The affected flower heads contain one white maggot, or a brown puparium.

Most records for this species come from the southern half of Britain, although it has on occasion been recorded further north.

Status in Leicestershire and Rutland not known.