MEGALOPTERA: Dobsonflies & Alderflies

This is a small Order of Insects, with some 300 species. "They are the most primitive insects that develop by complete metamorphosis", and "Both families have soft bodies and are drably colored with two pairs of large wings of almost equal size." [McGavin 2002: p. 103] The larvae (a Dobsonfly larva is shown above), called Hellgramites, live in the bottom of rivers and streams for several years, undergoing a number of larval stages during which they feed voraciously on other small water creatures. They crawl out of the water to pupate, making a chamber in sand, soil, or moss, and the adults live for only a few days after emerging, their sole purpose being to mate.

This hellgramite below was one of several uncovered beneath small rocks in the perennial portion of the San Pedro River near the upstream end of the Three-links Ranch in March 2007. Naturalist Elaine Nakash suggests it may be a Corydalus cognatus. Note the "eight pairs of simple filaments with basal gill tufts", and the much longer "prolegs at the end of the abdomen" (McGavin 2002:103). The sub-conical tip of the pen has a length of 13 mm (9/16"), which gives an indication of how large this larva is.