Urophora affinis Frfld. and U. quadrifasciata (Meig.) (Diptera: Tephriti- dae) are Eurasian gallicolous fruit flies introduced to North America in 1972 as biological control agents for Centaurea biebersteinii DC (spotted knapweed, Asteraceae, = C. maculosa auct. non Lam.) (Harris 1980). Through natural dispersal and numerous introductions, both Urophora species have become distributed throughout the introduced range of C. biebersteinii (Foote et al. 1993, Lang et al. 1997, Mays and Kok 2003).
Marshall, Jordan M.
"Parasitism of Urophora Affinis (Diptera: Tephritidae) by Aprostocetus Sp. (Hymenoptera: Eulophidae) in Michigan,"
The Great Lakes Entomologist, vol 40
Available at: https://scholar.valpo.edu/tgle/vol40/iss2/7