Urophora jaceana


The fly Urophora jaceana has a larva that produces galls on the flower heads of Common Knapweed which incorporates the receptacle and achenes. The gall is hard and woody; usually affecting most of the flower head; usually with several chambers, each with one larva.

Identification difficulty

Adult Gall


Wherever Common Knapweed is found.

When to see it

Galls from August to April, or puparium May and June (in old flower head).

UK Status

Widespread and fairly frequent in Britain.

VC55 Status

Probably fairly frequent in Leicestershire and Rutland but not well recorded.

Leicestershire & Rutland Map


Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map