The majority of Act57B^ex8/Df(2R)E2 animals die before pupating. In the brains of Act57B^ex8 homozygous larvae, the ellipsoid body (EB) is abnormal. The observed phenotypes fall into three classes: The most severe "unfused" phenotype, where termini fail to intersect at the midline, is observed in over half of the mutants (57%); A less severe "elongated" phenotype is seen in one-third of the mutants, where the EB processes cross the midline, but are abnormal in width (28%); The least severe "ventral" phenotype, where the EB width is normal, but the ventral processes fail to close the rings, is also the least frequent (15%).