ABSTRACT Bermudagrass (Cynodon dactylon cv. Jiggs) is an important food source for dairy cattle in the semi-intensive milk production systems most often used in southern Brazil. Although many insect pests are associated with feed grasses, we report here the first occurrence of the fly Atherigona (Atherigona) reversura Villeneuve, 1936 (Diptera: Muscidae) feeding on bermudagrass in Brazil. This potential pest was observed in April 2015 in three localities (Abelardo Luz, Palmitos, and Videira) in western Santa Catarina, in southern Brazil. The infested plants had senescent and necrotic terminal leaves that reduced plant growth. New growth had to sprout new tillers from basal nodes, which resulted in a reduced plant growth rate. We also provide a morphological identification key (with figures) for A. (Atherigona) reversura and A. (Acritochaeta) orientalis Schiner, 1868. A molecular identification based on COI is also provided to better differentiate species.