Anax Leach,1815 - GreenDarners

Fig. 1:Anaxlongipes
Larvacollected from the ESGR, Livingston Co., Michigan, USA

Notes -Michigan SpeciesList - Key -References
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Page last updated: 23October 1998 (EB)

Notes on theMichigan Species of Anax

The genus Anax is widespread intemperate and tropical regions of the world. Four species are foundin the New World, two of which are found in Michigan (Map 1-2). Theseare large nymphs found in still waters (ponds, lakes and stillportions of streams) clinging to aquatic vegetation.

Map1Map 2
Michigan county distribution of
A. junius (map1) and A.longipes (map 2).
Click on map for a larger image.

A. longipes(Fig. 1) recently has been added to Michigan's Odonata list(Kielb andO'Brien 1997), with a thrivingpopulation found in several experimental, fishless ponds at theUniversity of Michigan's E. S. George Reserve in Livingston County,southeastern Michigan (Map 2). Among our largest odonate larvae,mature nymphs exceed 60 mm in total length. Emergence from this siteappears to occur from mid-June through early August (Figure2).


Figure 2: Exuvia ofAnax longipesion cattail (Typha latifolia) from an experimental pond at the
E. S. George Reserve, Livingston County, Michigan.

A. junius is acommon resident of small and large lentic habitats throughoutMichigan where fish predation is not a significant factor. I havealso found them in very slow-moving waters with ample aquaticvegetation in slow-moving stream waters. Apparently two populationswith different emergence periods exist in the northern part of itsrange (Trottier1966, 1971). One (non-resident) population apparently migratesnorthward to oviposit in spring, with larvae rapidly developing untila September emergence, subsequently with newly emerged adultsmigrating southwards. Another cohort apparently stays year-round,with ovipositing occurring in July, with some egg diapause andsubsequent larval development during winter and spring until a Juneemergence. Work should be done to determine whether these populationscan be genetically distinguished.

Other links with information on the biology orecology of larval Anax:
none found as of 20 January 1998

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Michigan Species List

Anax junius (Drury,1773) - Common GreenDarner
Anax longipes
Hagen, 1861 - Long-legged Green Darner

Key toMature Larvae of Michigan Anax
(Adapted from Needham and Heywood1929 and Needham and Westfall1955)

1. Totallength of mature nymph >60 mm; folded labium passes metacoxatowards first abdominal segment (Fig. 2); labial lobes clearlytruncated (Fig. 3) - A.longipes

Fig. 2Fig. 3
Fig. 2-3. Anax longipes exuvia, collected by M. Kielb as larva on 06 August1996, with adult emerging on 14 August 1996. From the E. S. GeorgeReserve, Livingston County, Michigan. UMMZODO-1811.

1a.Totallength of mature nymph <55 mm; folded labium clearly does notreach beyond metacoxa (Fig. 4); distal edge of labial lobes somewhatrounded (Fig. 5) - A.junius

Fig.4Fig.5
Fig. 4-5: Anax junius, collected from Long Lake in Newago Co., Michigan, on11 September 1926 by T. H. Langois & P. A. Moody.UMMZODO-1307.

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References

Drury, D. 1773.Illustrations of natural history. Vol. 2. White: London. 90pp.

Hagen, H. A. 1861.Synopsis of the Neuroptera of North America, with a list of the SouthAmerican species. SmithsonianMiscellaneous Collections4:1-347.

Kielb, M. A.,and M. F. O'Brien. 1997. Discovery of an isolated population ofAnax longipes in Michigan (Odonata: Aeshnidae). Great LakesEntomologist 29(3):161-164.

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

Needham, J.G., and H. B. Heywood. 1929. A Handbook of the Dragonflies of NorthAmerica (Anisoptera). C. C. Thomas: Springfield, Illinois. 378pp.

Needham, J.G., and M. J. Westfall. 1955. A Manual of the Dragonflies of NorthAmerica (Anisoptera). University of California Press: Berkeley,California. x + 615 pp.

Trottier, R. 1966.The emergence and sex ratio of Anaxjunius Drury (Odonata: Aeshnidae) inCanada. The CanadianEntomologist 98:794-798.

Trottier, R. 1971.Effect of temperature on the life-cycle of Anax junius (Odonata:Aeshnidae) in Canada. The CanadianEntomologist 103:1671-1683.

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