Mutation causes semi-lethality with death of a high proportion of first instar larvae, allowing 20% of mutants to emerge from the pupal case. Adult escapers are characterised by partially unfolded wings with loss of venation and reduced size (more in their width than their length). Wing phenotype may vary from nearly normal wings to warped wings with a rough texture reflecting a higher density of trichomes. Escapers also exhibit poor viability and sterility, 25% of females give rise to viable progeny. First instar larvae remain essentially immobile with tracheal trees partially filled with fluid. The tracheal system is completely formed but exhibits a failure to completely replace solute by gas.