ecd2 homozygotes, ecd2/Df(3L)R-R2 and ecd2/ecdl(3)23 animals die after a prolonged L2. Most ecd1/ecd2 animals die during the L2/L3 molt, displaying typical molting defects such as double mouth hooks, but some survive into L3. Larval Lethality in ecd2 homozygotes is not rescued by feeding with 20-hydroxyecdysone (50 μg/ml or 250 μg/ml). ecd2 homozygous somatic clones induced at 24-36 hours after egg laying do not survive in wing or eye discs to late third instar. The resulting adults appear normal. However, such clones induced at the onset of the third instar do survive in late third instar eye discs. ecd2 homozygous clones in the ovary cause egg chamber fusions, typically producing egg chambers with double the normal number of germ cells. Egg chambers in which all germ cells are part of ecd2 homozygous germ-line clones arrest development early in oogenesis, showing degeneration of nurse cells, resulting in female sterility.
Hemizygous larvae die 48 to 72 hours after hatching, failing to survive the moult to the second instar stage. ecd1/ecd2 transheterozygotes die as they moult to the third larval instar; most die during ecdysis, with the old cuticle often remaining attached to the posterior end of the abdomen. The number of macrochaetae on the thorax is reduced in ecd1/ecd2 flies kept at 29oC in the hours that follow prepupal formation.
Temperature upshift at egg-laying or early third instar caused larval lethality. Temperature upshift at puparium formation causes pharate adult lethality.