With very few exceptions homozygotes fail to hatch, those that do are nearly immobile and die within a few hours. Although failing to hatch, most embryos complete the large part of embryogenesis prior to their death. Little evidence for tissue disorganisation or morphological abnormality is seen. The G2 progeny of PhmP(29) adults rescued by PhmA5.hs have apparently normal central nervous systems (CNSs) about 3/4 of these embryos complete embryogenesis and hatch, about 3/5 reach pupal stages and about 1/5 complete metamorphosis. Puparium formation is often aberrant: puparia typically display a slight curvature, a failure to shorten normally, and a failure to evert anterior spiracles properly. The gas bubble fails to move anteriorly, leaving pupae in anterior position with abnormal posterior gas spaces. The majority of these non eclosing puparia die after completing pupation and proper eversion of the head wing and legs, but reveal no further adult differentiation, dying between stages P4ii and P7. Many animals also reaching the same stage display aberrant disc eversion, retention of larval mouthparts and imprecise elimination of apolysed tracheal cuticle. Almost none of the prepupae that fail to eclose differentiate past stage P7. Daily heatshock inductions do not increase the survival of these G2 animals.