Homozygotes show only 3% embryonic lethality, and show 92% larval lethality. Most homozygous larvae die as small first instar larvae, although 27% advance to the third instar stage. The mutant larvae grow much slower than their control siblings.

13% of uif^1A15/Df(2L)Exel7029 animals die as embryos, and all those embryos that hatch die as larvae.

10% of uif^1A15/uif^2B7 animals show embryonic lethality, and all those embryos that hatch die as larvae.

Mutant larvae spend very little time in the food and instead wander around the plate, even if they appear to have mostly inflated trachea (a behaviour that has been shown to be a response to hypoxia).

Mutant third instar larvae show a tracheal moulting defect in which two tracheal cuticle layers and occasionally three cuticular layers are seen.

Homozygous third instar larvae have a reduced ratio of partial tracheal length (the distance along the dorsal trunk from the posterior spiracle to the transverse connective that originates in body segment A4) to total body length compared to wild-type controls.