Urbanization is a major driver of biodiversity loss, particularly in regions with weak environmental governance. While concerns about sustainable urban development and biodiversity conservation are increasing, urban planning rarely considers lower vertebrates and invertebrates. This study conducted a field survey in Nepal’s Kathmandu Valley, comprising Kathmandu, Lalitpur and Bhaktapur districts, to assess how butterflies respond to urban expansion. We classified the valley into urban, suburban, and rural zones using GIS-based multi-criteria analysis that incorporated population density, road network density, and vegetation cover (NDVI). Butterfly data were collected across 105 randomly selected sampling points, proportionally distributed across the zones. At each site, a 500 m × 10 m transect, subdivided into alternate three sampling units of 100 m × 10 m, was surveyed for butterfly abundance and environmental variables, with minor adjustments (± 100 m) as needed. We considered variables related to vegetation, disturbance, habitat and local climate to collect the field data. Statistical inferences and generalized linear models revealed that butterfly richness and diversity decline along the urbanization gradient, with the highest diversity in rural and suburban areas and the lowest in core urban areas. However, urban areas still support a substantial portion of the butterfly fauna. Local-scale environmental factors, particularly microclimate and vegetation, strongly influenced butterfly communities. Diversity was positively associated with ambient temperature and shrub cover and negatively associated with forest cover. Notably, the positive effect of temperature was more pronounced in urban areas, even under varying levels of tree cover, suggesting that warmer microclimates can sustain diverse butterfly communities despite urban stressors. These findings highlight complex interplay between microclimatic conditions and landscape context in shaping urban butterfly diversity. They underscore the importance of targeted urban greening strategies, such as expanding shrublands and supporting urban gardens, for effective biodiversity conservation. Incorporating butterfly-friendly vegetation into urban design can help cities serve as vital refuges for pollinators, enhancing both ecological integrity and human well-being.

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