Mutant flies hold their wings out, and halteres down. Some flies are capable of limited vertical wing movement. Wing hinge, blade and thorax show no readily detectable abnormalities. The expressivity of the phenotype in adults is unaffected by temperature. Direct flight muscle 49 and basalar muscle 51 are present and normal. Muscle of first axillary 53 and third axillary 54 sclerites are also present and normal, as is subalar muscle 57. The anterior dorsal mesothoracic nerve is also apparently normal.

Incapable of flying or folding wings back to the resting position. Halteres also hang alongside the body.