DR. JOHN BRACKENBURY / SCIENCE PHOTO LIBRARY DR. JOHN BRACKENBURY / SCIENCE PHOTO LIBRARY
Canada thistle gall fly. Close-up of a Canada thistle gall fly (Urophora cardui) on a flower. This fly is indigenous to Central Europe from the United Kingdom east to near the Crimea, and from Sweden south to the Mediterranean. It's larvae form galls (swellings) in the stems of creeping thistle (Cirsium arvense) plants. As a result these flies have been introduced to North America to help control the spread of these plants. Photographed in the UK, in July.
Model release not required. Property release not available.