Adults are about 3/8 inches long. Their coloration is dark gray, non-metallic, thorax lacking distinct stripes but with numerous short golden hairs, and the abdomen with irregular lighter areas. They are slow-moving and when the crushed smell of buckwheat honey. Cluster flies occupy attics and/or between-wall voids of walls which receive the most sunlight when they are ready to hibernate. They usually try to use the same structure year after year. While they are there they will not multiply.