Recombination between the loxP sites present in the two progenitor insertions (Mi{w+.loxP}bbgMI04312-loxP and Mi{w+.loxP}MI03323-loxP) has resulted in deletion of the intervening genomic sequence. This removes two large 5' exons of bbg, which code for specified regions of the long (bbg-RC and bbg-RK) and medium (bbg-RJ) isoforms. An element containing two copies of a w+* marker separated by a single loxP site remains at the site of the deletion.