Pollenia rudis, the common cluster fly, is a species of fly in the family Calliphoridae.Pollenia rudis is also known as the attic fly, the loft fly,pollenie du lombric , and the buckwheat fly. During the autumn and winter months, Pollenia rudis can be found overwintering inside of attics or lofts. This sluggish species can be found “clustering” near the interior windows of a warm structure.