Aquatic Insects of Michigan

by Ethan Bright, Museum of Zoology Insect Division and School of Natural Resources and Environment
University of Michigan

Nehalennia (Coenagrionidae) (Sprites) of Michigan - Identification

Of the four Nearctic (and one Palaearctic) species of the genus, two have been recorded in Michigan. Nymphs of N. irene are found among the macrophytes, sedges, cat-tails and other emergent vegetation in a wide assortment of aquatic habitats, including still areas of streams and rivers, sloughs and ponds, and sometimes bogs. I. gracilis, on the other hand, appears to be restricted to sphagnum bog habitats, with nymphs found near and alongside the margins of floating bog mats. Both species may be locally abundant in their particular habitat. Adults are small and slender, attractively blue and/or metallic green and black damselflies, emerging from mid-May through July. Walker (1953) remains an excellent reference resource for the species of our area.

Taxonomic References: Paulson (2011), Walker (1953) and Westfall and May (2006)

Key to Adults

1a	a. Ventral portion of Ab2-3 modified as secondary genitalia	Males, 2
	b. Terminal end of Ab10 with a pair of flanking claspers (caudal appendages)
1b	a. Ab2 venter morphologically undifferentiated from adjoining segments	Females, 3
	b. Distal portion of Ab8 sternum with a genital aperature, with a well-developed ovipositor underneath Ab9 and beyond
2a(1a)	a. Dorsum of Ab8 blue, with a transverse basal greenish black line or spot	Nehalennia gracilis Morse
	b. Ab9-10 entirely blue
	c. Paraprocts in lateral view with an apical tooth projecting rearward
2b	a. Dorsum of Ab8 greenish black, with a subtriangular blue spot extending anteriorly 1/4 the length of the segment	Nehalennia irene (Hagen)
	b. Ab9-10 blue, with dark metallic green spots on Ab10 at least 1/3 the length of that segment
	c. Paraprocts in lateral view with apical tooth projecting dorsally
3a(1b)	a. Posterior margin of prothorax bilobate, with two broad, lateral lobes, and a relatively slender median lobe projecting almost vertically	Nehalennia gracilis Morse
	b. Posterior margin of each mesostigmal plate with a slender medial lobe projecting almost vertically
3b	a. Posterior margin of the prothorax trilobate, with three, approximately equal, lobes, the median lobe lying almost flat over the mesothorax	Nehalennia irene (Hagen)
	b. Posterior margin of each mesostigmal plate without a slender medial lobe, but laterally raised into a large ear-shaped flange

Mature Nymphs

1a	a. Gills with numerous marginal and submarginal spots	Nehalennia irene (Hagen)
	b. Posterolateral surface of head with about a dozen small spines on each side, darkened at the base and distinct
	c. Wide assortment of aquatic habitats
1b	a. Gills nearly unspotted	Nehalennia gracilis Morse
	b. Posterolateral surface of head with 4-6 indistinct and nearly colorless spines
	c. Sphagnum bog habitats

References

Paulson D. 2011. Dragonflies and damselflies of the East. Princeton Field Guides. Princeton University Press, Pinceton, New Jersey, USA. 538 p.
Walker EM. 1953. The Odonata of Canada and Alaska, Volume One, Part I: General, Part II: The Zygoptera - Damselflies. University of Toronto Press, Toronto, Ontario. 292 pp.
Westfall MJ, May ML. 2006. Damselflies of North America, Revised Edition. Scientific Publishers, Gainesville, Florida, USA. xii + 502 pp.

Page created: 11 August 1998 - Last updated: May 19, 2020 (EB)