Early life stages and adult MacNeill's sootywing (Hesperopsis gracielae MacNeill, Family: Hesperiidae), a small butterfly, were searched for at ten conservation/wildlife areas along the Lower Colorado River Valley. This butterfly can only complete development on quailbush (Atriplex lentiformis (Torr.) S. Watson, Family: Amaranthaceae). In most cases quailbush was intentionally planted at conservation areas for wildlife purposes. Evidence of sootywings was found at nine of the locations. A single location had low numbers of the larval food plant and this may have resulted in non-detection of the butterfly. Early life stages of sootywings were associated with quailbush that had statistically higher soil moisture at the plant base. Plants where early life stage sootywings were detected (n=41) averaged 63 ± SE 6.3% soil moisture, while those where sootywings were not detected (n=109) averaged 37 ± SE 4% soil moisture. Soil moisture and appropriate densities of quailbush appeared to be important attributes for support of MacNeill's sootywing populations. Size of quailbush and presence of nectar in the environment were not statistically important attributes in presence or abundance of sootywings.