Different lady beetle species may be more or less successful predators of aphids that are protected by ants. If non-native lady beetles, for example, are better able to avoid, tolerate, and/or counteract protection by ants, this may have implications when non-native lady beetles co-exist in the same locations as native lady beetles. Interactions between seven different lady beetle species (Coccinella septempunctata, Harmonia axyridis, Propylea quatuorodecimpunctata, Hippodamia variegata, Coccinella trifasciata, Hippodamia convergens, and Coleomegilla maculata) and the European fire ant (Myrmica rubra) tending potato aphids (Macrosiphum euphorbiae) were compared in laboratory arenas using aggression and reaction scores. The aggression score evaluated behaviors exhibited by ants when encountering lady beetles and included avoidance, prolonged antennation, mandibles opening, grasping, and stinging. Reaction scores evaluated lady beetle behaviors when encountering ants, and included retracting legs, preening, turning on back, flailing legs, fluttering wings, walking away, and flying away. Ants displayed a significantly greater amount of aggression towards H. convergens and H. variegata compared with P. quatuorodecimpunctata (F=9.68, p <.0001). Similarly, P. quatuorodecimpunctata, C. trifasciata, and H. axyridis exhibited significantly lower reaction scores compared with H. variegata, H. convergens, C. maculata, and C. septempunctata (F=10.18, p<.0001). Aphid consumption and responses to ant stings also differed between lady beetle species. Differences in interactions with natural enemies may explain, in part, the successful establishment of some non-native coccinellids in new habitats.