The larvae and pupae of most caddisflies (Trichoptera) are aquatic, whereas the adults are terrestrial. However, the trichopteran genus Nothopsyche includes species with terrestrial pre-pupal and pupal stages and with an entirely terrestrial life cycle. The phylogenetic relationships within this genus, inferred from sequences of mitochondrial 16S and nuclear 18S ribosomal RNA genes, suggest that Nothopsyche species were originally aquatic and that a single lineage acquired tolerance to terrestrial habitats at the pre-pupal and pupal stages. In this lineage, N. montivaga became completely terrestrial. In addition, the larval case materials changed from plant matter to sand at one point in the phylogeny of this genus.