Mature larvae are large sprawlers in loose substrates, distinctive for their very long, slender legs with simple, slender long tarsal claw, and oval, broad abdomens adorned with sharp, cultriform dorsal hooks. Larvae are frequently found in larger streams as well as channels and lakes. They are absent from stagnant waters. Members of this family are most diverse in warmer regions of the world, with a few species extending into colder regions. Three species in two genera of Macromiidae are found in Michigan: Macromia illinoiensis and Didymops transversa are commonly encountered in most parts of the state, with Macromia taeniolata encountered along the larger rivers in the SLP where the current is slow and woody debris has fallen into the river.
1a. Lateral spines of Ab9 extend to or beyond tip of epiproct (picture); Ab10 without small middorsal hook or carina (picture); width of head behind eyes roughly equal to that across eyes (picture); lateral setae 5, premental setae 5 + 1-2 (picture) - Didymops
1b. Lateral spines of Ab9 short of tip of epiproct (picture); Ab10 with a small middorsal hook or carina (picture); width of head narrows posteriorly behind eyes (picture); premental setae 6, premental setae 5-6 + 3-4 (picture) - Macromia
Hilsenhoff, W. L. 1995. Aquatic insects of Wisconsin. Keys to Wisconsin genera and notes on biology, distribution and species (3rd Ed.). Publication Number 3 of the Natural History Museums Council, University of Wisconsin-Madison (1995).
Walker, E. M., and J. S. Corbet. 1975. The Odonata of Canada and Alaska, Vol. 3. University of Toronto Press: Toronto, Ontario. xvi + 308.