Organisms within this order have stout bodies with tough skins and cling to the underside of stones within swift areas of a riffle (Corydalids) or burrow into the substrate in muddy areas of a stream (Sialids). Both are active predators and spend much of their time hunting for other macroinvertebrates. The appendages on the body of these organisms are called "lateral abdominal gill filaments" and should not be mistaken for legs.

  Dobsonflies, alderflies, and fishflies are pollution sensitive organisms which are primarily found within upper reaches of the River, from the Mid Valley upstream. Corydalids are fairly common in the River and large specimens of this family have often been found in the Forest City area. The smaller Sailids are rarely found.

	Family: Corydalidae Genus: Corydalus (Dobsonfly or Hellgramite)
	Family: Corydalidae Genus: Nigronia (Fishfly)
	Family: Sialidae Genus: Sialis (Alderfly)