Imprecise excision of the progenitor insertion, resulting in a deletion that removes part of the dco gene and part of the Sox100B gene.
Sox100Bj3B9-rvL/Df(3R)tll-e flies (Df(3R)j3B9-rvL/Df(3R)tll-e animals in which dco function has been rescued using dco+t13.1) survive to the pharate adult stage or die shortly after eclosing from the pupal case.