This genus occurs essentially worldwide. These flies are generally well-sized and of a greyish color; like many of their relatives, the typical patterns are lengthwise darker stripes on the thorax and dark and light square dots on the abdomen. Many have conspicuous red compound eyes. These are set further apart in females than in males; the females are also larger on average. As typical for this family, it is almost impossible to tell the species apart from their outward appearance, and many can only be reliably identified by microscopic examination of the males' genitalia.