Order: Megaloptera - Fishflies, Dobsonflies (hellgramites) and Alderflies

Natural History: Most of the organisms that we call benthic macroinvertebrates (bottom dwelling animals without backbones that we can see without magnification) are fairly small.  As may be obvious from their name, MEGAlopterans are not small (except when they are young - lower right).  Pictured here is a fishfly larva, in the family Corydalidae.  Fishflies are often confused with hellgramites, which are a close relative.

Fishflies are voracious predators in our Potomac streams that hunt in the cobble on stream bottoms.  Be careful - they will bite. They cling strongly to rocks and are rarely swept into the water column. Unlike hellgramites, fishflies do not have well developed, tufted gills along the abdomen.  Rather, they absorb dissolved oxygen using the lateral filaments arrayed along the abdomen, and are also able to utilize atmospheric oxygen using retractable breathing tubes that extend from the top of abdomen.

They live as larvae for up to three years. At the end of this period, they transform during a brief pupal stage into a flying adult. The adults are weak fliers whose "purpose" is to mate and late eggs. The eggs are laid in masses on rocks, vegetation and even bridges that overhang the water. When the eggs hatch, the larvae drop directly into the water below.

Pollution tolerance: Moderate (4 out of 10)

Location: Skaggs Run, Hardy County