Imprecise excision of the progenitor insertion.
fs(1)hPA hemizygotes have a cuticular phenotype, and show disruption of the head skeleton.
fs(1)hPA/fs(1)h1 females are fertile at 18[o]C, but lose fertility at 25[o]C.
Progeny from fs(1)hPA/fs(1)h1 mothers, raised at semipermissive temperatures (22[o]C), do not hatch. Cuticle analysis reveals very severe head defects, and 95% show segmental fusion of the second abdominal segment. Defects are rarely observed in other segments. The filzkorper is often deleted or malformed.