Hemizygotes show reduced viability, with female escapers being completely sterile. Homozygotes also show reduced viability, but female escapers are fertile. Approximately 35-40% of the total hemizygous or homozygous lethality of Catsup¹¹ occurs during the third larval instar stage. Lethality also occurs during pupariation. Dying third instar larvae have a distinctive "melanotic salivary gland" phenotype; individual cells of the salivary glands begin to melanise until, most commonly, the entire salivary gland is a completely black, mulberry-shaped organ. In the more severe cases, a secondary site of melanisation is seen in the mid-dorsal region, probably in the lymph glands, which then spreads throughout the haemolymph. Hemizygous prepupae show large regions of internal melanisation and pupal cases are darker than normal, especially after aging. Most prepupae that die start autolysis but cannot undergo metamorphosis, producing empty or partially empty pupal cases. Pupae and pharate adults undergo severe, abnormal melanisation and show varying degrees of incomplete cuticle formation. The cuticle is relatively normal on the head, thorax and legs, but is incompletely formed over much of the abdomen. There is an absence of bristle and tergite formation in the posterior abdominal region. The pharate adults appear to have normal cuticles (which are thinner than normal but have well-defined epicuticles and procuticles with normal appearance), but they lack an epidermis in the regions with incomplete cuticle. Adult escapers often have minor malformations of the cuticle, primarily on the abdominal tergites. 5-10% of Catsup¹¹ heterozygous adults have melanotic pseudotumours.

Hemizygous and heterozygous larvae show variable degrees of promiscuous melanisation. All or some salivary gland cells may become melanised in third instar and occasionally second instar larvae. Melanisation is also seen in the mid-dorsal region in some cases, and these larvae never pupariate. Other larvae pupariate, producing pupal cases that are initially darker than wild-type. These pupal cases become even darker on aging, and many have large irregular regions of internal melanisation. Some animals pupate, producing relatively normal cuticle on the head and thorax, but having extensive regions of incomplete cuticle on the abdomen. Large areas of the incomplete cuticle are usually melanised. Adult escapers often have a few abdominal segments with incomplete cuticle and frequently have large internal melanotic tumours.

Melanized puparia and pharate adults, with incomplete head and thoracic cuticle, no abdominal cuticle and no eyes or bristles.