Transheterozygotes with other alleles produces rare escapers, which have an extreme mutant phenotype; wings and halteres similar to those of an extreme vestigial allele; eyes, although large, have rough glazed appearance and the flies are almost achaetous, having fewer than ten macrochaetae per fly; acrostichal hairs and other microchaetae reduced in number and disturbed in arrangement; tarsal claws also much reduced.
Littlewood.