Several of these in shallow water of the Upper Tees. Just seen very similar on Springwatch described as caddis fly larva.
No interactions present.
These are of the family Limnephilidae and are grazing the algae that grow on the rocks in spring. Difficult to know the species without microscopic examination, but the very dark colour suggests to me Melampophylax mucoreus or Allogamus auricollis, but others are almost equally possible. All I am sure of is that they are of this family and in what is called the single filamented gill group.
Ian Wallace, UK Trichoptera Recording Scheme
Lat/Lng: 54.6317, -2.1117
OS grid ref: NY928262