This study was conducted in a 1-hectare field of maize, Zea mays L., near Rio Bravo, Tamaulipas during the fall growing seasons of 2011 and 2012. The objective was to document the competitive displacement of the crambid stalkborers Diatraea lineolata (Walker) and D. saccharalis (F.) by Eoreuma loftini (Dyar), after the invasion of the latter species from Western México into this area during the early 1980's. All larvae collected by sampling fields and adults emerging from pyramid cages were identified as E. loftini during both years. According to previous studies in the same region, D. lineolata and D. saccharalis were the only corn stalkborers during the 1970's, with dominance of the former species. During the 1980's, after invasion by E. loftini, the three species coexisted, with D. lineolata still dominating. This study showed E. loftini is now the dominant stalkborer species in this agroecosystem. Although the displacement by E. loftini is evident, D. linelolata and D. saccharalis are not likely to be extint from this area, but rather they probably were not abundant enough to be detected by the sample size used in this study. Factors probably related to the displacement of D. lineolata and D. saccharalis by E. loftini are discussed.