Many flies that contain mutant clones have pits or protrusions on the thorax in the vicinity of the flight muscle attachments.
When mutant clones are induced in the wing, a wing blister appears within a few minutes of eclosion of the adult flies from the pupal case.
Mutant clones in the pupal wing completely lack the transalar microtubule arrays that are normally seen spanning the wing cells at this stage. This results in an expansion of the mutant cells and a contraction of the wild-type cells in the opposing epithelial layer. The two epithelial sheets of the wing remain associated.
Homozygous embryos complete development but the tracheae appear twisted and broken and the cuticle detaches from the epidermis.
Homozygous clones in the wing produce large blisters that lack sharp boundaries. Wings are sometimes rumpled. Homozygous embryos show excessive contractions of the segmental muscles just before hatching. The posterior segments are compacted and the muscles appear shorter than normal.