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Landscape associations of the sand fly, Lutzomyia apache, Young and Perkins, in the southwestern U.S. were investigated by light/suction trap sampling and the development of a GIS-generated distribution map. In the mid-Rio Grande River valley, N.M., female and male L. apache were captured in updraft light/suction traps set in desert shrubland, irrigation levee, and bosque vegetation communities. Small numbers of flies were captured, but the presence of males and females in spatially separate and diverse plant communities at two locations Suggest that L. apache are dispersed among available vegetation types. These data, along with 22 previously published collection site records, were used with a suite of physiographic features to characterize the biogeographic conditions suitable for L. apache. Suitable conditions encompass three life zones: the Rocky Mountain steppe province. the Colorado semi-plateau province, and the American semi-desert province. all within the dry domain region of the western U.S. The potential range of L. apache was then estimated based on elevation, mean and max-min temperature. precipitation, wet days, and relative humidity. The estimated range includes large contiguous areas in north-central Colorado, east-central New Mexico and west Texas, the lower mid-Rio Grande River valley. and southern Arizona, along with smaller, patchy, areas in northern Arizona, California, Nevada. Utah. and central Idaho. The spatial relationship between the estimated distribution of L. apache and the location of livestock exposed to vesicular stomatitis virus at the onset of recent outbreaks is presented.