released as classical biological control agent[ ] to control the invasive weed, yellow starthistle ... Currently the fly is widely distributed throughout the range of yellow starthistle in California ...

Adult female flies oviposit in closed flower buds of starthistle and developing larvae stimulate the formation of lignified, unilocular galls, which are partially submersed in the receptacle ...

[study concludes that] Gall densities did not reach levels needed to exert significant control of seed production

- Woods, Dale M., Michael J. Pitcairn, Donald B. Joley, & Charles E. Turner: (2008) Seasonal phenology and impact of Urophora sirunaseva on yellow starthistle seed production in California^©