Homozygous lethal, with the majority of mutants failing to survive beyond the second or early third larval instar stages. Many of the dying larvae retain larval mouth hooks from the L2 molt, and in some cases L2 and L3 mouth hooks are malformed, indicating a defect in cuticle shedding. Mutant larvae exhibit sluggish movement, even though they retain normal olfactory functions, touch sensitivity and phototaxis. Feeding mutant larvae with ecdysone does not affect these phenotypes.
Homozygous mutants eventually stop moving and appear to attempt pupariation. However, they fail to evert their spiracles and frequently turn brown but never produce a pupal cuticle. Many larvae develop interior necrotic patches, suggestive of larval hematopoiesis defects.