Abstract
Drosophila melanogaster is an insect that can walk on smooth surfaces, and its tarsal segments bear a pair of footpads that are equipped with spatulate-shaped hairs (setae). We found that narrow (B) ( nw (B) ) mutants, an allele of the nw gene, were unable to climb smooth surfaces, due to the destruction of the footpad hair tips. The mutant hair tips were damaged during molting from the pupal cuticle at eclosion. Thus, the nw gene encoding a secretory protein that serves as an extracellular matrix is implicated in the formation of the footpad hairs.