Detritivorous beetles of the temperate deciduous forest biome thrive in low-nutrient environments with an abundance of cellulosic material, and it is speculated that yeast endosymbionts aid in the metabolism of such materials within the gut of these beetles. To investigate the biodiversity of microbes in this niche, we isolated over 200 yeast strains from different beetles living in the Pennsylvania area. Isolates contained representatives from both Ascomycete and Basidiomycete fungi, including several putatively novel species. Phylogenetic analysis characterized the evolutionary relationship of isolated yeasts; physiological and morphological growth tests helped to characterize the phenotypes of novel species. Interestingly, we found that the majority of yeast endosymbionts were able to metabolize xylose, a five carbon ‘woody sugar,’ faster than glucose. This research contributes to the study of yeast biodiversity in a particular niche and future characterized strains could improve methods used for lignocellulosic biofuel production.