Life-history data are presented relating to three common Lepidoptera which belong to the recently demonstrated insectan fauna of rushes in the zone of emergent hydrophytes of northern Michigan lakes: 1. Nepticula sp., (Nepticulidae), is a semiaquatic miner in sedges; all other known North American species of the genus are nonaquatic leaf-miners in shrubs or trees. The food plants of this species are: Scirpus occidentalis (Watson) Chase, S. validus Vahl, A. americanus Persoon, and Eleocharis palustris (L.) Roemer & Schultes var. major Sonder. Eggs, larvae, mines, and cocoons are described. 2. Schoenobius melinellus dispersellus Robinson, (Pyralidae, Schoenobiinae), bores in culms of Eleocharis palustris (L.) Roemer & Schultes var. major Sonder or rarely in Carex vesicaria L. and Scirpus americanus Persoon. Life-history stages of an American schoenobiine are described for the first time. Two larval and one egg parasite were bred from the species. 3. Occidentalia comptulatalis (Hulst), (Pyralidae, Crambinae), feeds chiefly upon Scirpus occidentalis (Watson) Chase in the region studied. Two other lacustrine bulrushes, S. validus Vahl and Sc. americanus Persoon are occasionally eaten. Habits and life history stages of the moth are described. Two egg and two larval parasites were studied.