Abstract
The limnephilid caddisfly Hesperophylax occidentalis was collected from July 1978 through June 1979 from spring sources in the Piceance Basin, Colorado. H. occidentalis preferred the spring habitats to area streams downstream from spring sources. H. occidentalis exhibited a univoltine life cycle with extended emergence (April-October) and hatching (June-December) periods. Growth occurred mainly during autumn or winter depending on the time of egg laying. Gut analyses and laboratory observations showed that H. occidentalis can obtain food by several methods and will consume the most available food item.