Genophantis leahi was a species of moth in the family Pyralidae described by Otto Herman Swezey in 1910. It was endemic to the Hawaiian islands of Maui, Oahu, Molokai and Hawaii. The wingspan was usually 20 mm or less. The larvae fed on , Euphorbia cordata, Euphorbia hirta and . The larvae hid in a web spun between adjacent leaves and along the stem. They ate one surface and mesophyll of the leaf, leaving the other epidermis. Fully grown larvae were about 15 mm long and light yellowish, with blackish stripes.