Progeny of mothers carrying one copy of this allele show loss of head and thoracic structures without a mirror image duplication of the posterior segments, though a few embryos are bicaudal. Mothers carrying two copies of the transgene produce entirely bicaudal embryos with an average of 2.5 abdominal segments in each orientation. The central fused denticle band in these embryos is frequently narrower and smaller than those for osk^mob.bcd.UTR embryos. Anterior pole cells do not form.