The hellgrammite (Family Corydalidae), or dobsonfly larvae, is a quite distinctive group. The larvae is elongate with the head possessing a well-developed mouthpart. A hellgrammite is predacious in nature and is quite active in the water; it has been known to bite fisherman who try to collect it for bait. An abdominal segment has a pair of lateral filaments and tufted gills that allow this organism to obtain dissolved oxygen from streams and rivers.

The hellgrammite is usually found in well-oxygenated water and is, therefore, an indicator of good water quality. They are among the better water quality indicators that WPC Watershed Assistance Center biologists examine in evaluating the health of streams.

Today's photo was taken by WPC's Jennifer Bennett, Watershed Technician II.