Hr4¹ mutants die as prepupae. They are also smaller than controls. Approximately 5% of the mutant third instar population are 'dwarf' larvae, that do not feed and are unable to pupariate. They eventually perish as almost transparent larvae due to depleted fat stores. This extreme growth defect is likely caused by a very early onset of wandering behavior.

Hr4¹ hemizygous animals die at the prepupal stage. Hr4¹ hemizygous prepupae show a range of defects: failed head eversion; failed or partial anterior spiracle eversion; incomplete tanning of pupal case; failure of gut clearing. These animals are also often significantly shorter and lighter than wild-type. Many Hr4¹ hemizygous larvae stop feeding and start wandering earlier than wild-type larvae (who exhibit this behaviour in late L3), some even exhibit this behaviour during L2. Non-feeding larvae are smaller than wild-type and prematurely initiate mobilization of stored nutrients through autophagy (assessed by marking of fat body vesicles with Lysotracker Red). In addition, 20%-70% of these mutants initiate metamorphosis early, with some forming prepupae 28 hr after the L2-to-L3 molt, almost a day earlier than wild-type. Unlike wild-type larvae, pupariation of Hr4¹ hemizygotes is not inhibited by transfer to sugar only diet 12-17 hours after the L2-L3 molt. Also unlike wild-type, around 30% of Hr4¹ hemizygotes pupariate in the presence of cycloheximide.