Distribution: Brachycentrus subnubilus is mainly distributed in Northern and Western Europe; the spreading area includes Scandinavia, East- and North-Russia, Western Europe with the British Islands, the Iberian Peninsula, Central Europe, Italy and the northern Balkan.

Habitat: Aquatic stages of Brachycentrus subnubilus develop in large rivers and streams in lower regions and can even be found in brackish water (Tobias & Tobias 1981, Robert & Wichard 1994, Waringer & Graf 1997, Wallace et al. 2003). The species is vicariating with Brachycentrus montanus (Pitsch 1993). Larvae need moderate current and structures to attach the case to, for they filter particles from the water stream with their second and third legs (Wallace et al. 2003).

Nutrition: Merritt & Wallace (1981) give a precise description of the feeding behaviour of Brachycentrus-larvae: larvae fix their case onto the substrate and hold the middle and hind legs against the current to filter small particles from the water; long setae, inserting on the thoracic tergites, prevent the intrusion of matters into the case; coarse particles like Copepoda or Cladocera are caught with the extremities, while fine particles are sieved by a dense fringe of setae, inserting on the lower margin of the legs.

Adults: Adults are present from March to June (Waringer & Graf 1997).