Mutant embryos show defects in dorsal closure, head involution and midgut constrictions. The mutant embryos stall in tracheal branching morphogenesis at stage 14. Despite the stall in morphogenesis, the embryos move within their eggshell and accumulate chitin in the epidermis during stages 16 and 17. A 2 hour exposure of 5-7 hour embryos to 20-hydroxy-ecdysone is sufficient to rescue the morphogenetic defects and produce viable first instar larvae, but treatment of older embryos has little rescuing effect.