Aquatic Insects of Michigan
by Ethan Bright, Museum of Zoology Insect Division and School of Natural Resources and Environment
Megaloptera of MichiganIntroduction
This small holometabolous order has just two families, Corydalidae (Dobsonflies, Fishflies) and Sialidae (Alderflies), both of which occur in Michigan. There are normally 10-11 larval instars, and life cycles of most species are 1-3 years, with emergence in late spring or early summer. Larvae of all species are carnivorous; little is known about the feeding habits of our short-lived adults.
The larvae of Corydalyidae are known as hellgrammites. Eggs are laid terrestrially, proximate to water, and hatch rapidly 3-5 days after laying, with first instar larvae dropping into the water. Larvae are predacious, feeding principally on mayflies, dragon- and damselflies, caddisflies and dipterans. After growth of 2-5 years, larvae leave the water for a distance of 20-35 cm (but can be considerably farther) to a log or moist terrestrial environment to construct a pupal chamber. Adults are short-lived, generally poor fliers, emerge at night and fly into trees to locate each other and mate. Adults are photophilous, and are often collected in light traps and ordinary street or house lights. Males have large mandibles, obstensively for courtship purposes.
Alderfly larvae generally inhabit depositional silt in lentic and lotic environments. Life history is very similar to Corydalidae: females oviposit eggs terrestrially, often in large numbers on vegetation proximate to water. Eggs hatch rapidly 3-5 days after laying, with the first instar larvae dropping into the water. Larvae are predacious, feeding principally on small mayflies and midges. Larvae are both lentic and lotic, usually burrowing into depositional areas of silt. Common in littoral zones of some lakes, but also can be found further out from shore.There are 10 larval instars requiring 1-2 years to reach the terminal larval instar. Pupation is terrestrial, and adults do not feed. Adults are short-lived and are generally poor fliers. Adults are not photophilous; larvae and adults lack ocelli. One must either collect them on the wing or among nearby vegetation. Sialid larvae are distinct from corydalids in that the last abdominal segment does not have anal claws, but rather has a long, slender median terminal filament.Genera are denoted in green; species denoted in bold blue have been recorded in Michigan; species denoted in black bold are likely to occur in Michigan based on their known distribution with nearby state/provincial localities from which certified records have been published. You can use the Find function in your web browser to locate families, genera, and species. Synonomous species (indented) are listed below the current valid species (denoted in bold) with its taxonomic status indicated.
Five species in four genera are recorded from Michigan, with one additional species possibly to be encountered in the state based on existing regional distributional records. Neohermes concolor is known in Michigan only from several blacklight-collected specimens from the extreme southwestern Lower Peninsula. Michigan specimens of Nigronia fasciatus in the UMMZ-Insect Division were determined by the author to be misidentified N. serricornis. However, based on this species known distribution, it may occur in the southern part of the Lower Peninsula.
Chauliodes Latreille 1796 (Subfamily Chauliodinae)
Neohermes Banks, 1908 (Subfamily Chauliodinae)
Nigronia Banks, 1908 (Subfamily Chauliodinae)
Sialis americana (Rambur, 1842) Semblis (orig.)
Sialis hasta Ross, 1937 - Ross 1937: 74; Canterbury 1978: 27-29, 89
Sialis infumata Newman, 1838 - Ross 1937: 73; Canterbury 1978: 34-36, 89
Sialis itasca Ross, 1937 - Ross 1937: 72; Canterbury 1978: 87
Sialis joppa Ross, 1937 - Ross 1937; Canterbury 1978: 43-46, 89; Tarter et al. 1978: 232
Sialis mohri Ross, 1937 - Ross 1937: 74; Canterbury 1978: 43-46, 87
Sialis vagans Ross, 1937 - Ross 1937: 77; Canterbury 1978: 39-41
Sialis velata Ross, 1937 - Ross 1937: 71; Canterbury 1978: 46-47, 87
Davis KC. 1903. Part 7. Sialididae of North and South America, pp. 442-486 in Aquatic insects in New York State. New York State Museum Bulletin 68: 442-487.
Hazard EI. 1960. A revision of the genera Chauliodes and Nigronia (Megaloptera: Corydalidae). M.S. thesis, The Ohio State University, Columbus, Ohio, USA. iii + 53 pp.
Ross, HH. 1937. Studies of Nearctic aquatic insects. I. Nearctic alder flies of the genus Sialis (Megaloptera, Sialidae). Bulletin of the Illinois [State] Natural History Survey 21:57-78 [Errata: printed on a free slip of paper inserted in the work].
Penny ND, Adams PA, Stange LA. 1997. Species catalog of the Neuroptera, Megaloptera, and Raphidioptera of America North of Mexico. Proceedings of the California Academy of Sciences 50(3): 39-114.
Tarter DC, Waktins WD, Little ML, Ashley DL. 1977. Seasonal emergence patterns of fishflies east of the Rocky Mountains (Megaloptera: Corydalidae). Entomological News 88(3-4): 69-76.
Tarter DC, Watkins WD, Ashley DL, Goodwin JT. 1978. New state records and seasonal emergence patterns of alderflies east of the Rocky Mountains (Megaloptera: Sialidae). Entomological News 89(9-10): 231-234.
November 07, 2012
Page created: November 01, 2002; Last updated: July 18, 2016 (EB)