P{lArB} insertion 57bp from the 5' end of the bab1 transcript. There is a strong reduction in the amount of bab1 transcript produced and no bab1 protein is produced.
Homozygous flies have no leg or ovary defects. Females show defects in abdominal pigmentation; ectopic dark pigmentation is seen in the anterior portion of tergites A6 and A7.