Cystiphora sonchi is a species of gall midge in the family Cecidomyiidae. It is native to Eurasia, but has been introduced to North America as a biocontrol of sow thistles. The larvae cause small, circular galls on the leaves of the host plants.[1] Several species of parasitic wasps use the larvae as hosts.
This species was first described as Cecidomyia sonchi by Swiss entomologist Johann Jacob Bremi-Wolf in 1847.