Production of maize, Zea mays L., for forage at Chiapas, México, is important for animal feed. However, with a recent objective to produce more forage, association of maize with other crops including Johnsongrass, Sorghum halepense (L.) Pers., has increased. But association has brought infestation by new pests. The objective of this research was to identify the sugarcane aphid, Melanaphis sacchari (Zehntner), as a pest in the associated crop. We reported for first time the aphid affecting the crops at Chiapas, Mexico. The cytochrome c oxidase I (COI) gene was compared with the GenBank database and the aphid was identified molecularly as Melanaphis sacchari with 95% similarity. Its predators were identified as: Chrysoperla externa (Hagen) 99% similarity, Hippodamia convergens Guerin-Meneville, and Cycloneda sanguinea (L.). The last two were morphologically identified.