Aquatic Insects of Michigan

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

Sympetrum (Libellulidae) (Meadowhawks) of Michigan - Identification

Nine of the 15 species of Sympetrum in North America north of Mexico have been recorded in Michigan. Found amongst aquatic vegetation in shallow marshy bays, ponds, swamps and slow-moving streams, larvae are small, slender sprawlers and climbers, mottled with green and brown (Walker and Corbet 1975). Most species are lentic, generally collected from circumneutral ponds, though S. costiferum may sometimes be encountered in bogs (Kormondy 1958), and the Holarctic species such as S. danae in marshy ponds and bogs on peaty soils (Walker and Corbet 1975).

Adults are often small, clear-winged individuals dragonflies that are often seen on flight throughout much of autumn. Males of many species have attractive reddish bodies, that of the female brownish yellow. Adults often are seen far from water bodies. Sympetrum nymphs closely resemble those of Leucorrhinia but have unpigmented abdominal sterna and lack a middorsal spine on abdominal segment 3. Tai (1967) observed that the eggs of some species undergo obligatory diapause in development, low water temperatures apparently triggering embryonic development. Eggs can also survive dessication, thus some species can develop in temporary water bodies (e.g., Cannings 1980). Like other species (e.g., Tramea, Pantala) some species developing in ephemeral aquatic systems have rapid growth, with 7-10 instars completed in 57 to over 100 days. Walker and Corbet (1975) noted that S. corruptum are mulitvoltine, and Whitehouse (1941), Turner (1965) and Opler (1971) suggested this may be the result of two populations, one migratory, the other resident (see also Anax). One of last group of Michigan dragonflies to emerge, adults appear from late June through August and are seen flying as late as October and early November.

Taxonomic references: Needham et al. 2010, Paulson 2011, Walker and Corbet 1975

Adults

1a	a. Tergum of Ab4 with supplementary transverse carina in basal 1/3, at least in females	Sympetrum corruptum (Hagen)
	b. Forewings often each with two cell rows between veins Rs and Rspl
	c.Hamules each with ventromedial branch a stout hook, much shorter than dorsolateral branch
	d. Subgenital plate a thickened, bilobed ridge forming distal margin of sternum of Ab8
	also: Wings hyaline at base; usually 7 antenodal crossveins in each forewing, 5 in each hindwing; legs largely black with extensor surfaces yellow; lateral carinae of abdomen black; subgenital plate much less than 1/2 length of sternum of Ab9
1b	a. Tergum of Ab4 without a supplementary transverse carina in basal 1/3	2
	b. Forewings each with one cell row between veins Rs and Rspl
	c. Hamules each with ventromedial branch nearly as long as (although often much more slender than) dorsolateral branch
	d. Subgenital plate not as above
2a(1b)	a. Male cerci, in lateral view, each with dorsal margin smoothly convex and without prominent ventral tooth	3
	b. Genital lobes more or less spatulate and directed posteroventrally
	c. Hamules each with dorsolateral branch projecting posteroventrally
	d. Subgenital plate formed by distal margin of sternum of Ab8, entire or slightly emarginate and projecting slightly to strongly downward apically
2b	a. Male cerci, in lateral view, with dorsal margin concave in apical half and with prominent ventral tooth	6
	b. Genital lobe tapered and directed almost posteriorly
	c. Hamules each with dorsolateral branch projmecting posteriorly
	d. Subgenital plate distinct from distal margin of sternum of Ab8, strongly bilobed, not projecting downward apically
3a(2a)	a. Basal 1/2 of hindwings predominantly transparent saffron	Sympetrum semicinctum (Say)
	b. Ab9 with lateral carinae
3b	a. Basal 1/2 of hindwings predominantly hyaline (sometimes saffron in female S. danae)	4
	b. Ab9 without lateral carinae
4a(3a)	a. Pterothorax largely black or dark brown with pattern of yellow spots	Sympetrum danae (Sulzer)
	b. Terga of Ab4-7 extensively black above lateral carinae
	c. Pterostigmata brown or black dorsally
4b	a. Pterothorax pale or with narrow black or brown stripes on sutures only	5
	b. Terga of Ab4-7 with black, if present, confined to narrow stripe along lateral carinae
	c. Pterostigmata yellowish or reddish dorsally
5b(4b)	a. Legs predominantly black	Sympetrum costiferum (Hagen)
	b.Lateral carinae of abdomen black
	c. Hamules each with medial hook shorter than lateral lobe
	d. Subgenital plate not strongly projecting ventrally
5b	a. Legs predominantly yellow	Sympetrum vicinum (Hagen)
	b. Lateral carinae of abdomen not black
	c. Hamules each with medial hook longer than lateral lobe
	d. Subgenital plate strongly projecting ventrall
6a(2b)	a. Tibiae predominantly yellowish brown	Sympetrum ambiguum (Rambur)
	b. Rear of head without ridges lateral to occiput
	c. Abdominal black markings consisting of apical, transverse bands
6b	a. Tibiae predominantly black	7
	b. Rear of head with short, transverse ridges lateral to occiput
	c. Abdominal black markings, if present, consisting of lateral stripes or triangles
7a(6b)	a. Hamules each without medial prominence or tubercle on dorsal lobe	Sympetrum rubicundulum (Say)
	b. Subgenital plate inflated, about as high as long
	c. Femora offemale usually extensively pale, at least on flexor surface
7b	a. Hamules each with distinct medial prominence or tubercle on dorsal lobe	8
	b. Subgenital plate not inflated, about half as high as long
	c. Femora of female usually predominantly black on flexor and extensor surfaces
8a(7b)	a. Pterothorax with metathoracic venter densely hairy across entire surface	Sympetrum internum Montgomery
	b. Cerci pale, those of male with dorsal margins barely concave in apical 1/2
	c. Costa usually mainly yellow
	d. Ventromedial branches of hamules contiguous apically in natural position
	e. Subgenital plate with ventral ridges curved posterolaterally
8b	a. Pterothorax with metathoracic venter not densely hairy except sometimes along lateral carinae	Sympetrum obtrusum (Hagen)
	b. Cerci usually reddish with dark apices, those of male with dorsal margins strongly concave in apical 1/2
	c. Costa usually mainly brown
	d. Ventromedial branches of hamules not contiguous apically in natural position
	e. Subgenital plate with ventral ridges directed posteriorly
	also: Dorsal lobe of each hamule truncate apically with its posteromedial process tuberculate, and with ventral hook ofhamule not extended posteriorly beyond dorsal lobe; ventral surface of subgenital plate flatly tapered to acute apices, directed posteriorly

Mature Nymphs

1a	a. Abdomen without dorsal hooks	Sympetrum corruptum (Hagen)
	also: Metafemur at least 5.9 mm long; epiproct at least 1.5 mm long; cercus at least 0.9 mm long; long palpal setae 13 or more on each side (additional much shorter setae may be present)
1b	a. Abdomen dorsal hooks on at least Ab5-7	2
2a(1b)	a. Dorsal hook on Ab4 absent or vestigial	3
2b	a. Dorsal hook clearly present on Ab4	5
3a(2a)	a. Dorsal hook present on Ab8, often vestigially present on Ab4	Sympetrum obtrusum (Hagen) [in part]
	also: Lateral spines of Ab9 about 0.25x the lateral length of segment, normally not extending beyond posterior margin of Ab10
3b	a. Dorsal hooks completely absent from Ab8 and Ab4	4
4a(3b)	a. Lateral spines of Ab9 shorter, about 0.2x lateral length of segment (including spine)	Sympetrum internum Montgomery
4b	a. Lateral spines of Ab9 longer, about 0.25x lateral length of segment (including spine)	Sympetrum danae (Sulzer)
5a(2b)	a. Lateral spines of Ab9 extending beyond tips of cerci by at least 1/3 the length of cercus	6
5b	a. Lateral spines of Ab9 not, or barely, extending beyond tips of cerci	7
6a(5a)	a. Lateral spines of Ab8 barely 2x as long as their basal width, those of Ab9 about 2.5x their basal width	Sympetrum semicinctum (Say)
	b. Outer margins of lateral spines of Ab9 distinctly convex
	c. Cerci longer, 0.5x as long as paraprocts
	d. Paraprocts not acuminate
6b	a. Lateral spines of Ab8 more than 2x as long as their basal width, those of Ab9 about 3x their basal width	Sympetrum vicinum (Hagen)
	b. Outer margins of spines of Ab9 nearly straight
	c. Cerci shorter, less than 0.5x as long as paraprocts
	d. Paraprocts slightly acuminate
7a(5b)	a. Lateral spines of Ab9 less than 1/3x the lateral length of segment (including spine), usually not extending beyond posterior margin of Ab10	Sympetrum obtrusum (Hagen) [in part]
	also: Dorsal hooks stouter, distinctly curved, that on Ab7 distinctly less than middorsal length of Ab7
7b	a. Lateral spines of Ab9 more than 1/3x the lateral length of segment (including spine), often extending beyond posterior margin of Ab10	8
8a(7b)	a. Dorsal hook of Ab8 in dorsal view extending posteriorly barely beyond anterior margin of Ab9	Sympetrum costiferum (Hagen)
	also: Dorsal hook on Ab4 small but sharp and erect
8b	a. Dorsal hook of Ab8 in dorsal view extending posteriorly over at least 1/3 middorsal length of Ab9	9
9a(8b)	a. Dorsal hook of Ab8 in lateral view slender, about 3x as long as its basal width	Sympetrum ambiguum (Rambur)
	b. Dorsal hooks of Ab4-5 not erect, in lateral view forming an angle of less than 45° with the long axis of the body
9b	a. Dorsal hook of Ab8 in lateral view stout, about 2x as long as its basal width	Sympetrum rubicundulum (Say)
	b. Dorsal hooks of Ab4-5 more or less erect, in lateral view forming an angle of more than 45° with the long axis of the body

Needham JG, Westfall MJ, May ML. 2010. Dragonflies of North America, Third Edition. Scientific Publishers, Gainesville, Florida, USA. xiv + 657 p.
Opler PA. 1971. Mass movement of Tarnetrum corruptum (Odonata: Libellulidae). Pan-Pacific Entomologist 47:223.
Paulson D. 2011. Dragonflies and damselflies of the East. Princeton Field Guides. Princeton University Press, Pinceton, New Jersey, USA. 538 p.
Turner PE. 1965. Migration of the dragonfly, Tarnetrum corruptum (Hagen). Pan-Pacific Entomologist 41:66-67.
Walker EM, Corbet JS. 1975. The Odonata of Canada and Alaska, Vol. 3. University of Toronto Press: Toronto, Ontario. xvi + 308.
Whitehouse FC. 1941. British Columbia dragonflies (Odonata), with notes on distriubtion and habits. American Midland Naturalist 26:488-557.

Page created: July 17, 1998 - Last updated: February 18, 2017 (EB)