Horned Knapweed Fly

Terellia ceratocera can reach a wing length of 4.3–6.4 millimetres (0.17–0.25 in). These fruit flies have frons, thorax and legs yellow. Eyes are blue-green. The anterior portion of the mesonotum bears a dull black mark. Katepistemum shows a black triangular mark. Pedicel of the males is greatly enlarged. The abdomen is dark orange with paired black marks on tergites 4 and 5. Wings bear four distinct and straight dark bands.

This species can be found from Britain up to western Siberia and central Europe (Albania, Andorra, Austria, Belgium, Britain, Bulgaria, Central European Russia, Czech Republic, Denmark, East European Russia, eastern Palearctic realm, Estonia, Finland, France, Germany, Italy, Lithuania, Norway, Poland, Romania, Slovakia, Sweden, Switzerland and the Netherlands), Balkans, Turkey and Kazakhstan.