Df(3R)Tpl^JE5 heterozygous flies (carrying one copy of Tpl) die in the embryonic stage. Before death, the midgut turns brown (and is the first tissue to die), and tracheal development is abnormal. This is accompanied by more widespread cell death, and then the tracheae appear to break up and turn brown. Soon thereafter, the entire animal dies. These flies are also developmentally-retarded (they exhibit the embryo phenotype at a time when the wild-type would have already hatched to the first instar larval stage).