RK2. The anterior part of the abdomen is constricted. Wings are frequently held abnormally, and have a longitudinally undulating surface. Most flies die shortly after emergence, but viable and fertile males are occasionally produced.
RK3. Anterior part of abdomen constricted, giving appearance of long, narrow waist. Wings held abnormally and surface wavy. Most flies die shortly after eclosion, but occasional male is viable and fertile.