A monotypic genus, Hagenius brevistylus is most certainly Michigan's most distinctively shaped odonate larva (Fig. 1). The very flat abdomen is broad, nearly circular in outline, bearing dark mid-dorsal hooks and sharp lateral angles on abdominal segments 2-9. This shape is shared by other gomphid genera in other parts of the world and appears related to the habit of burrowing in leafy trash (Corbet 1962). Both Needham and Westfall (1955) and Walker (1958) provide an excellent description of the larva.
This species is widely distributed in Michigan (Map 1). Larvae are shallow sprawling predators, concealed within loose substrates overlain with leafy or woody debris in streams and protected areas of lakes and marshes environments. Aquatic samples frequently result in several size classes of larvae, which take upwards to 4 years to mature, in Michigan emerging from the third week of June to early July (Walker 1958, and pers. obs.). This species appears to be found throughout the state.
Hagenius larva encrusted with Zebra Mussels. Douglas Lake, Cheboygan Co., MI 2008. Photograph by P. Myers, Animal Diversity Web
Other papers with information on the biology or
ecology of larval Hagenius:
Burcher, C.L. and L.A. Smock. 2002. Habitat Distribution, Dietary Composition and Life History Characteristics of Odonate Nymphs in a Blackwater Coastal Plain Stream. American Midland Naturalist, 148(1):75-89. DOI: http://dx.doi.org/10.1674/0003-0031(2002)148[0075:HDDCAL]2.0.CO;2
Fincke, O, D. Santiago, S. Hickner, and R. Bienek 2009. Susceptibility of larval dragonflies to zebra mussel colonization and its effect on larval movement and survivorship. Hydrobiologia 624:71–79. DOI 10.1007/s10750-008-9667-7
Corbet, P. S. 1962. A biology of dragonflies. E. W. Classey Ltd.: Oxon, England.
Needham, J. G. and M. J. Westfall, Jr. 1955. A Manual of the Dragonflies of North America (Anisoptera). University of California Press: Berkeley, California. 615 pp.
Selys-Longschamps, E. de. 1854. Synopsis des Gomphines. Bulletin de l'Académie royale des Sciences de Belgique 21(2):23-112(sep. 3-93).
Walker, E. M. 1958. The Odonata of Canada and Alaska, Vol. 2. University of Toronto Press: Toronto. xi + 318 pp.