The coleopteran Stethobaroides nudiventris was found in flowers of the epiphytic orchid Catasetum integerrimum and the ant Paratrechina longicornis in the Trichocentrum cebolleta epiphytic orchid in the field. This is the first report of S. nudiventris at Tamaulipas, expanding its distribution in northeastern Mexico, and is the second record as a visitor to the orchid. This is the first report of P. longicornis in flowers of T. cebolleta. Knowledge of potential orchid pollinators and pests is of utmost importance as a reference for future studies, because the knowledge is scarce in the northern Neotropical zone.