Rank: RK1 Mutant flies have a bellows-like appearance in the tergites and look bulgy in the abdominal segments. The anterior and posterior peripheries of the dark pigmented bands of the tergites appear to be tucked inside the epidermis. The phenotype is conspicuous in the second to fifth tergites, but weak in the sixth tergite. The tucked-in cuticle can be extended by pressing the abdomen, suggesting that the cuticle component is left intact. The phenotype is enhanced with age.