In homozygotes, lethality acts at the 2nd or 3rd larval instar. Wings of heterozygotes with bs03267 form tubes, formed exclusively of vein cells.
Clones of bs13 show an autonomous mild wing phenotype. Ectopic veins are observed only when they occur in the vicinity of the anterior crossvein and vein L5. However dorsal veins overlying ventral clones are widened and blisters extend beyond clone borders.
Chromosome carrying bs13 is pupal/pharate adult lethal but the basis for the lethality is not clear. Alleles fall into a series in ascending order of severity: bsA48 < bs11 < bs12 < bs13 < bs14 < Df(2R)bs-F31.