Hawaii's remarkable biodiversity, with over 9,300 endemic species of plants, animals, and fungi, serves as an exceptional example of evolutionary diversification. The Hawaiian Drosophilidae, a unique radiation of flies originating from a single colonization event approximately 25 million years ago, exemplify adaptive radiation within this unique ecosystem. This dissertation explores the intricate relationships between the distribution and vulnerability of Hawaiian Drosophilidae and various environmental variables, providing comprehensive insights into their ecological requirements and informing conservation strategies. In the first chapter, I conducted a detailed analysis of distribution data at different taxonomic hierarchies, employing statistical models such as random forest and generalized additive models to assess the influence of moisture zone, land cover, and elevation on species richness and diversity. The findings revealed that agricultural land, shrub and brush rangeland, and evergreen forestland are significant predictors of richness and diversity, with species group-specific responses across islands. Host specialists, particularly those utilizing bark, were found to be commonly restricted to high elevation environments and are more at risk for extinction. These results highlight the need for tailored conservation strategies to address the complexity of factors influencing Hawaiian Drosophila distribution and vulnerability. The second chapter revisits historical data from the Waikamoi Forest Preserve, collected by J.P. Murphy between 1965-1968, to evaluate shifts in community composition in response to invasive species, habitat modification, and climate change. Analyses of this historical data underscore the sensitivity of Hawaiian Drosophila to ecological changes and the significant seasonal impacts on their richness and abundance. This work emphasizes the importance of incorporating historical survey data into conservation efforts to effectively address the challenges posed by rapid environmental changes and the escalating threats of invasive species. The third chapter compiles surveys of Hawaiian Drosophila conducted in the Waikamoi Preserve on Maui from the 1960s to modern collections to examine species persistence and potential declines over the past 50 years. The study found a stark decline in Hawaiian Drosophila populations, largely driven by fluctuations in precipitation and exacerbated by the introduction of invasive species such as habitat-modifying invasive ginger and predatory Vespula wasps. Various management strategies employed in the East Maui watershed are discussed, with recommendations to maximize native plant and insect diversity while preserving access to water for agriculture and human consumption. Collectively, this dissertation provides a comprehensive analysis of the factors shaping the diversity and abundance of Hawaiian Drosophilidae. By understanding these relationships, we can contribute to conservation efforts aimed at preserving these unique species and their habitats in the face of ongoing environmental threats.