Coenagrion Kirby, 1890 - Bluets

Notes - MichiganSpecies List - Key -References
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Page last updated: 17 July1998

Notes on the Michigan Species of Coenagrion

Chiefly a Palaearctic genus, three species areknown from North America, of which two reach our area. Thesemoderate-sized damselflies closely resemble the larvae ofEnallagma and Ischnura, and diagnostickeys (Walker1953, Westfall and May1996) often include these species withEnallagma.Westfall andMay (1996) also believe that a commonlyused diagnostic - 6 vs. 7 antennal segments - is not reliable.

Larvae are widely distributed in northern latitudes, and is probablyunivoltine in Michigan.
Walker (1953, p. 179) notes that C.resolutum, which is widely distributedin Michigan (Map 1, below), inhabits a wide variety of lentichabitats, including "almost any small permanent or subpermanent bodyof still water...ordinary ponds and prairie sloughs with marshyborders; in springy cat-tail marshes; in dark calla ponds; insphagnum pools, in cool northern spruce or tamarack swamps, and inthe marginal vegetation of slow weedy streams."


Map 1: County distribution ofCoenagrionresolutum in Michigan
Click on map for a larger image

C. interrogatum, currently known only from one record on Isle Royal,inhabits cold swamps and open bogs, partial to areas of open bog ormarsh (Walker1953, p. 181-183).

Links on the biology or ecology of larvalCoenagrion:
no links found as of 15 January 1998

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Michigan Species List

Coenagrioninterrogatum (Selys, 1876) - Subarctic Bluet
Coenagrion resolutum (Selys,1876) - Taiga Bluet

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Key to Mature Larvae of MichiganCoenagrion
(Adapted from
Westfall and May1996)
Click on species' name for Michiganrange map

1a. Mediangill < 5x as long as wide, and usually slightly acuminate apically(picture); cerci of male without a dorsomedial concavity (picture);ovipositor rudiments of female extending more than 0.6 mm beyondposterior row of denticles on sternum of abdominal segment 9(picture); metafemur usually > 2.9 mm - C. resolutum

1b. Median gill ca. 5x as long as wide, and usually notacuminate apically (picture); cerci of male with distinct dorsomedialconcavity (picture); ovipositor rudiments of female extending <6.0 mm beyond posterior row of denticles on sternum of segment 9(picture); metafemur usually < 2.9 mm - C. interrogatum

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References

Kirby, W. F. 1890. A synonymic catalog of NeuropteraOdonata or dragonflies. Guerney and Jackson, London. 202 pp.

Say, T. 1839.Descriptions of new North American neuropterous insects andobservations on some already described by (the late) Th. Say.Journal of the Academy of NaturalScience of Philadelphia 8:9-46.

Selys-Longchamps, E.de. 1876. Synopsis des agrionines, cinquième légion:Arion(suite). Le genre Agrion. Bulletin del'Académie royale des Sciences de Belgique (2) 42:480-531.

Walker, E. M. 1953.The Odonata of Canada and Alaska, Vol. 1. University of TorontoPress: Toronto, Ontario. xi + 292 pp.

Westfall, M.J., Jr. and M. L. May. 1996. Damselflies of North America. ScientificPublishers: Gainesville, Florida. x + 650 pp.

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