Sesioidea is the superfamily currently containing clearwing moths (Sesiidae), castniid moths (Castniidae) and little bear moths (Brachodidae). There is evidence from head and thoracic morphology that the first two families, internally feeding in plants as caterpillars, are sisters, whilst some brachodids are known to feed on leaf surfaces (Edwards et al., 1999). Sesioidea are considered to be the sister group of Cossoidea which contain the also internal-feeding Goat and Leopard moths.
Edwards, E.D., Gentili, P., Horak, M., Kristensen, N.P. and Nielsen, E.S. (1999). The cossoid/sesioid assemblage. Ch. 11, pp. 181–185 in Kristensen, N.P. (Ed.). Lepidoptera, Moths and Butterflies. Volume 1: Evolution, Systematics, and Biogeography. Handbuch der Zoologie. Eine Naturgeschichte der Stämme des Tierreiches / Handbook of Zoology. A Natural History of the phyla of the Animal Kingdom. Band / Volume IV Arthropoda: Insecta Teilband / Part 35: 491 pp. Walter de Gruyter, Berlin, New York.
Firefly Encyclopedia of Insects and Spiders, edited by Christopher O'Toole, ISBN1-55297-612-2, 2002