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