Genophantis leahi was a species of moth in the Pyralidae family. It is endemic to Maui, Oahu, Molokai and Hawaii. The wingspan is usually 20 mm or less. The larvae feed on Euphorbia bifida, Euphorbia cordata, Euphorbia hirta and Euphorbia pilulifera. The larvae hide in a web spun between adjacent leaves and along the stem. They eat one surface and mesophyll of the leaf, leaving the other epidermis. Full-grown larvae are about 15 mm long and light yellowish, with blackish stripes.