The RED and HD domains of ey have been replaced by the RED and HD domains of eyg.
eye | ectopic, with Scer\GAL4dpp.blk1
As with overexpression of wild-type ey, expression of ey::eygEEGEGE.Scer\UAS, under the control of Scer\GAL4dpp.blk1, leads to the formation of ectopic eyes on appendages.