Most species of the genus Ameletus are found in the smaller, fast water streams of the higher altitude streams of the Western and Pacific states. Four species are worth noting, the velox, of the Sierra Nevada drainage, the sparsatus, common in the Yellowstone River and the Cooki. The ludens species is an Eastern mayfly. There is only one stage of life that is real important to anglers – the nymph. These mayflies crawl out of the water to hatch so it is not necessary to imitate the emergers or duns. The spinners are ocassionally important.