A distinctive species with a unique wing pattern. The scutellum and sides of the thorax are pale cream and the eyes have an orange-green reflection.

The fly produces galls in the flower heads of thistles, usually Spear Thistle, Cirsium vulgare. Part or all of the receptacle and achenes become a hard woody gall with one or more chambers.  The galls are not obvious but can be felt as hard lumps by squeezing dead flower heads.

Adult Gall

Anywhere that the host plant Spear Thistle is present.

Summer

The female lays her eggs in the flower heads of thistles, usually Spear Thistle, causing them to swell and damage seeds. They are sometimes used in weed control against thistles.

Fairly frequent in the southern half of Britain, but very few records from Scotland.

Fairly common in Leicestershire and Rutland