Measuring biodiversity remains a fundamental yet challenging issue in conservation biology. Drylands, major components of terrestrial biomes, are particularly susceptible to desertification due to climate change and human activities. In Venezuela, the highly threatened arid ecosystems of Margarita Island harbor unique biodiversity, yet beetle diversity remains poorly known, despite the value of beetles as models to guide conservation actions. Most beetle diversity and ecological studies in arid and semiarid ecosystems worldwide focus on ground-dwelling beetles. Therefore, beetle diversity in the arid environments of Margarita Island was assessed using three methods: pitfall trapping, yellow pan traps, and beating. The diversity patterns recorded for each sampling technique were compared in a one-year survey from May 2012 to April 2013, including dry and rainy seasons. Asymptotic species richness estimation was used to assess beetle richness at the study site. Coverage-based rarefaction curves and generalized linear mixed models were employed to compare variations in richness, abundance, and Shannon-Wiener diversity between methods and seasons. Compositional differences in assemblages were also assessed using multivariate methods. Some 152 species were found, and asymptotic richness was 185 species. Previous work listed 21 species of Tenebrionidae. We recorded 16 tenebrionids, of which 6 are new for the island. Eufallia seminivea (Motschulsky, 1866) (Latridiidae), Hyperaspis octomaculata (González, 2024), and the genera Zilus (Mulsant, 1850), Tiphysa (Mulsant, 1850) (Coccinellidae), Trichodesma (LeConte, 1861) (Anobiidae), and Neolitochrus (Gimmel, 2013) (Phalacridae) are recorded for the first time in Venezuela. Yellow-pan traps and beating showed the highest estimations of species diversity, highlighting the important contribution of vegetation-dwelling beetles to arid ecosystem diversity despite inherent methodological constraints.