Insect flightlessness may reflect adaptation to specific environmental pressures, such as a lack of predation, scattered food resources, or high winds and low temperatures. Statistical tests of the ecological correlates of flightlessness require that the taxa under study have evolved flightlessness independently, rather than having dispersed to new habitats after losing the ability to fly. Here, analysis of both molecular and morphological characters supports the hypothesis that two alpine-living moth species in the Hawaiian Islands have evolved flightlessness in isolation from each other. Both males and females of two Thyrocopa species have each not only lost the ability to sustain flight, but also have undergone wing reduction and locomote by jumping. This study provides evidence for strong parallel evolution in less than 1 million years, as well as suggesting certain ecological conditions that elicit loss of flight.