The adult Cluster is almost 8 mm long. She has a gray-black body, her abdomen is not striped with dark bands, but covered with small golden hairs, which tend to fall as they age.
The adult Cluster flies feats plant sap, fruit, flowers, excrement and animal meat protein. The larva feeds on earthworms by piercing its skin to feed on them from the inside.
The adult Cluster fly lives in outside near its food source, but in the fall, it has the distinction of entering the walls and the attic our buildings, hence its presence inside from the house during the winter, outside, it will spend the winter in the burrows of small animals, like the mouse. The larva will live inside one or more earthworms (worms) until it reaches adulthood.
The female lays between 100 and 300 eggs in a humid place where the vegetation is dense and where the soil humidity is very high, this kind of place is favourable to support a large earthworm population necessary for the development of its young.