This is a widespread family of dragonflies. Five of the eight species of Cordulegaster found in North America have been recorded in Michigan (see maps below).

Cordulegaster as a group is currently under considerable dispute, despite several attempts over the past two decades (e.g., Carle 1983, Lohmann 1992) to construct monophyletic groupings among species traditionally placed in this genus. In describing Zoreana bilineata, Carle (1983) elevates to genus the subgenera Cordulegaster (or Thecophora), Taeniogaster and Zoraena. Going even further, Lohmann (1992) argues that Cordulegaster is an Old World genus, and that the North American species are surviving and individual remnants of formerly speciose, distinct ancient groups. He grouped the eight North American species into the six genera. However, many researchers - especially in North America - are reluctant to accept these proposals (but see May and Carle 1996), and we follow the conservative practice of relegating Taeniogaster, Thecophora and Zoraena as subgenera of Cordulegaster (e.g., Westfall and Tennessen 1996). The table below summarizes the placement of Cordulegaster species:

Except for C. bilineata and C. diastatops, separation of the Michigan species of Cordulegaster is relatively straightforward. For those two species, however, no morphological description has been published that will separate the two species. In fact, there is considerable dispute whether C. bilineata is sufficiently distinct from C. diastatops to be regarded as a separate species. The larval forms appear very similar and may, in fact, not be disguishable from each other. Although the two species usually do not occur together ( Carle 1983), both species have been found in the same habitat in the northern part of its range. It is highly recommended that any pre-emerging larvae be reared and identification based on the adult form. I (EB) am currently trying to obtain specimens of both species to determine if there are larval characters that distiguish the two. In lieu of any peered-reviewed published information, I would label collected larvae lacking associated adult material of these two species as "C. diastatops or bilineata".

C. erronea is appears to be very rare in Michigan, and only one record appears to have been reported from the western part of the LP. This is mostly a southern species, and Michigan probably represents the northernmost part of its range. This species is on the State's Special Concern List. In Hocking Co., south-central Ohio, C. erronea inhabits sand substrates of forested seeps and spring-fed brooks with considerable slope (Dan Riggs, pers. comm.). C. obliqua tends to be found only in first-order, small sandy forest brooks, at least in the southern part of its range (Tennessen et al. 1995). Based on observations of adult C. bilineata and C. diastatops in Michigan, habitat tends to be sandy substrates of downstream pools and runs of hillside springs and brooks, both in forested as well as open or bushy pastures. This appears to agree with habitat descriptions for these species from other workers (e.g., Walker 1958, Tennessen et al. 1995). The rarity of specimens (particularly larvae) from our state reflects insufficient sampling of these habitats. Conversely, C. maculata (Figure 1), which inhabits larger forested creeks and streams with good water quality, is by far Michigan's (and Eastern North America's) most common cordulgastrid and is found throughout the state.

Larvae usually are found submerged under sand and silt, often protected under pieces of large woody or leafy detritus where they lie in wait for prey. Larvae are long-lived and probably require over three years in which to develop into adults, at least in the northern part of its range: three different size classes of larval C. maculata have been found in streams from Marquette Co., UP (EB, pers. obs.). Emergence of this species in the north appears to occur in early to mid-June, with females observed ovipositing in early July. Kennedy (1917) collected four size classes of C. dorsalis in California. Emergence occurs close to the waters edge, usually in June. Johnson (1982) studied prey selection of C. maculata from a stream in the Adirondack Mountains in New York, USA., and found that mayflies (Baetis sp. and Paraleptophlebia sp.) were the principal prey, with chironomids, simulids and caddisflies of various trophic relationships also important components. The author speculated that C. maculata in this stream are active foragers (apparently at night), as their principal prey (in this study, the mayflies) where not well represented in Surber samples that were used to collect larvae in the deeper sections of the stream. Unfortunately, the author did not account for drift in prey species, thus the observation must be considered speculative.

Other links with information on the biology or ecology of larval Cordulegaster (checked on 12 August 1998):
Cordulegaster sayi ESA status >>http://www.epa.gov/docs/fedrgstr/EPA-SPECIES/1994/October/Day-26/pr-24.html
Biology of C. sayi >> http://www.ims.usm.edu/~musweb/sayi.htm
Ottawa, Ontario survey, with brief habitat notes >> http://www.cyberus.ca/~jdsankey/odon2.html
UK Cordulegaster boltoni >>http://www.ex.ac.uk/~cnfrench/ics/cbru/monitor/corbol.htm

Map 1Map 2Map 3
Map 4Map 5
Maps 1-5: County distribution of the Michigan species of Cordulegaster
Click on map for a larger image

1a. Prementum wider at base, palpal width < 2.4x that of basal width (Figure 1a1); frontal shelf truncate in dorsal view (Figure 1a2), subacute in lateral view; lateral spines of Ab8 strongly upcurved (Figure 1a3); developing ovipositor of female about 0.7x length of Ab9 sternum (Figure 1a4) - C. diastatops or C. bilineata

Fig.1a1Fig. 1a2
Fig. 1a3Fig. 1a4
Fig. 1a1: C.diastatops larva, collected from Belchertown, MA, on 12 May 1938. leg. J. Needham? IORI loan.
Fig. 1a1-2: Ibid., 12.5x, dorsal view.
Fig. 1a3: 12.5x, lateral view.
Fig. 1a4: 6x, ventral view.
1b. Prementum narrower at base, palpal width > 2.5x that of basal width (Figure 1b1); frontal shelf appearing rounded in dorsal view (Figure 1b2), acute and ridge-like in lateral view; lateral spines of Ab8 not so strongly upcurved (Figure 1b3); developing ovipositor of female 0.9x or more the length of Ab9 sternum (Figure 1b4) - 2

Fig.1b1Fig. 1b2
Fig.1b3Fig.1b4
Fig. 1b1: C. erronea larva (12.5x, ventral view), from Camp Carding, Brevard, NC, collected by M. J. Westfall in August 1942. IORI loan.
Fig. 1b2: C. maculata larvae (12.5x dorsal view), from Packer Creek, Montmorency Co., MI, collected by D. Cuthrell and D. Hyde (MNFI) on 25 June 1996.
Fig. 1b3: C. erronea larva (12.5x, lateral view), from Camp Carding, Brevard, NC, collected by M. J. Westfall in August 1942. IORI loan.
Fig. 1b4: C. maculata larva (12.5x, ventral view), from Packer Creek, Montmorency Co., MI, collected by D. Cuthrell and D. Hyde (MNFI) on 25 June 1996.

Fig. 2a1
Fig. 2a1: C. obliqua exuvia (12.5x, dorsal view), locality and collector information missing. IORI loan.

2b. Palpal setae 4 or 5, premental setae 11 or less (usually 5-6+4-5) (Figure 2b1); developing ovipositor of female > 1.0x length of sternum of Ab9 (Figure 1b4) - 3

Fig. 2b1
Fig. 2b1: C. maculata larva (12.5x, dorsal view), from Packer Creek, Montmorency Co., MI, collected by D. Cuthrell and D. Hyde (MNFI) on 25 June 1996. UMMZODO-1393.

Back to previous couplet(2); Back to beginning of key

Fig. 3a1Fig. 3a2
Fig. 3a3
Fig. 3a1: C. erronea larva (12.5x, dorsal view), from seepage ditch in Monroe Co.,TN, collected by K. J. Tennessen on 24 July 1979. IORI loan.
Fig. 3a2: C. erronea larva (12.5x, dorsal view), from Highlands, NC, collected by M. J. Westfall on 22 June 1953. IORI loan.
Fig. 3a3: C. erronea larva (12.5x, dorsal view), from Camp Carding, Brevard, NC, collected by M. J. Westfall in August 1942. IORI loan.

3b. Lateral setae 5 (Figure 3b1); small round dots numerous, occupying ca. 1/2 the area of the frontal shelf (Figure 3b2); epaulets anteriorlaterally truncated in dorsal aspect (Figure 3b3) - C. (Thecophora) maculata

Fig. 3b1 Fig. 3b2
Fig. 3b3
Fig. 3b1: C. maculata larva (12.5x, dorsal view), from Packer Creek, Montmorency Co., MI, collected by D. Cuthrell and D. Hyde (MNFI) on 25 June 1996. UMMZODO-1393.
Fig. 3b2: Ibid.
Fig. 3b3: Ibid.
Back to previous couplet(2); Back to beginning of key

Carle, F. L. 1983. A new Zoraena (Odonata: Cordulegastridae) from Eastern North America, with a key to the adult Cordulegastridae of America. Annals of the Entomological Society of America 76(1):61-68.

Johnson, J. H. 1982. Diet composition and prey selection of Cordulegaster maculata Sel. larvae (Anisoptera: Cordulegasteridae). Notulae Odonatologicae 1(9):151-153.

Kennedy, C. H. 1917. Notes on the life history and ecology of the dragonflies (Odonata) of central California and Nevada. Proceedings of the United States Museum 52:483-635.

Leach, W. E. 1815. Entomology, pp. 52-172. In Brewster's Edinburgh encyclopaedia. Vol. 9. Edinburgh.

Lohmann, H. 1992. Revision der Cordulegastridae. 1. Entwurf einer neuen Klassifizierung der Familie (Odonata: Anisoptera). Opuscula Zoologica Fluminen 96:1-18.

May, M. L., and F. L. Carle. 1996. An annotated list of the Odonata of New Jersey, with an appendix on nomenclature in the genus Gomphus. Bulletin of American Odonatology 4(1):1-35.

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

Selys Longchamps, M. E. de. 1854. Synopsis des Gomphines. Bulletin de l'Académie Entomologique Belgique 21:23-114.

Selys Longchamps, M. E. de. 1878. Quatriemes Additions au Synopses des Gomphines Bull. Bulletin de l'Académie Entomologique Belgique 28:658-698.

Walker, E. M. 1958. The Odonata of Canada and Alaska, Vol. 2. University of Toronto Press: Toronto.

Westfall, M. J., Jr. and K. J. Tennessen. 1996. Odonata, pp. 164-211, in An Introduction to the Aquatic Insects of North America, 3rd Ed. R. W. Merritt and K. W. Cummins (eds.). Kendell/ Hunt Publishing Company: Dubuque, Iowa.