Positional cloning of a Bombyx wingless locus flugellos (fl) reveals a crucial role for fringe that is specific for wing morphogenesis.

Mutations at the flügellos (fl) locus in Bombyx mori produce wingless pupae and moths because of the repressed response of wing discs to ecdysteroid. Four recessive fl alleles occurred spontaneously and were mapped at 13.0 of the silkworm genetic linkage group 10.