Some homozygous escapers eclose at 25^oC. On average they require 5.5-6 days longer to develop than normal. At 18^oC eclosion of escapers is delayed by 14 days compared to wild type. Heterozygotes show no obvious phenotype. At the transition from second to third larval instar stage, homozygotes develop pigment encapsulated cell clusters, which gradually lose their cellular appearance and transform into dark brown to black inclusion bodies of variable size ("black pearls"). These melanotic "tumours" are found at arbitrary sites apparently without contact to the surrounding tissue. In surviving adults the tumours are located predominantly in the abdomen and less frequently in the thorax. The tumours stop growing in the adults and appear to be benign without obvious effects on longevity.

Germline clones produce eggs with patterning defects: variable segmentation defects.