The Brazilian Peppertree, Schinus terebinthifolia, is an invasive species in the Rio Grande Valley, posing a significant threat to local biodiversity by outcompeting native plants and disrupting ecological balance. Traditional control methods have proven inadequate, prompting the exploration of alternative solutions such as biological control agents. The chalcid wasp, Megastigmus transvaalensis, has shown promise as a biological control agent due to its host specificity, which minimizes the risk of non-target effects on native plants. The wasp targets Brazilian Peppertree seeds, reducing the plant's reproductive capacity. This study investigates the consequences of inbreeding within the wasp population, examining its effects on phenotypic variation and mate selection dynamics. Field samples revealed 10 phenotypes, varying in body color, wing pattern, and wing size. Additionally, the study assesses the effectiveness of M. transvaalensis in managing Brazilian peppertree populations. An analysis of 260 seeds collected from three areas (Raymondville, San Benito, Santa Rosa) showed infestation rates of 46%, 27%, and 32%, respectively, at different stages of parasitism. Field studies demonstrated that the presence of this parasitic wasp reduces the seed production of Brazilian Peppertree. The use of M. transvaalensis as a biological control agent presents a promising solution for managing this invasive species. However, further research is needed to optimize its use and integrate it effectively into invasive species management programs.