Aquatic Insects of Michigan

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

Leucorrhinia (Libellulidae) (Whitefaces) of Michigan - Identification

A genus of Holarctic distribution, seven species of Leucorrhinia are found in North America, with five found in Michigan. Adults are small, whitefaced, and (except for a dark basal spot) clear-winged dragonflies. These are some of earliest dragonflies on wing, and often abundant around bogs and wetlands. Nymphs are small, smooth and greenish in appearence with brownish markings, with slender legs; they are climbers amongst aquatic vegetation. Leucorrhinia are common in bog lakes and ponds with floating vegetation; however, L. intacta can be common in marshy bays, farm ponds and slow streams. L. hudsonica is a denizen of bogs and cold marshy ponds; it is a widely distributed boreal and montaine species with its southern range limit in Michigan. Similarly, L. glacialis and L. proxima are found along the margins of floating bogs and muskegs, the former species inhabiting the waters of high acidity. They are probably univoltine in our area.

Taxonomic references: Needham et al. 2010, Paulson 2011, Tennessen 2019, Walker and Corbet 1975

Adults

1a	a. Males	2
1b	a. Females	6
2a(1b)	a. Ab7 with prominent pale middorsal spot	3
	b. Cerci each with a distinct subapical ventral angulation in addition to ventral denticles
2b	a. Ab7 without a pale middorsal spot	4
	b. Cerci each with ventral denticles but usually without a distinct subapical angulation
3a(2a)	a. Epiproct bifurcated, the lateral margins widely divergent posteriorly	Leucorrhinia intacta (Hagen)
	b. When mature, middorsal yellow spot on Ab7 only
3b	a. Epiproct entire or emarginate at apex, the lateral margins not very strongly divergent posteriorly	Leucorrhinia hudsonica (Selys)
	b. When mature, middorsal spots on Ab4-7
4a(2b)	a. Wings each with two cell rows for length of 3 or more cells between veins Rs and Rspl	Leucorrhinia glacialis Hagen
	b. Forewings with 3 cell rows with trigonal interspace
	c. Anteroventral arm of each hamule, in lateral view, sinuate and sharply hooked at apex
4b	a. Wings each with one cell row between veins Rs and Rspl, or less often, with 1-2 doubled cells	5
	b. Forewings with 2 cell rows in proximal part of trigonal interspace
	c. If not b, then with anteroventral arm of each hamule in lateral view smoothly curved, not sharply hooked at apex
5b(4b)	a. Forewing with 3 cell rows in trigonal interspace	Leucorrhinia proxima Calvert
	b. Labial palps usually with a large pale, laterodistal spot
	c. Hamules in ventral view each without posterolateral angulation or process
5b	a. Forewing with 2 cell rows in trigonal interspace	Leucorrhinia frigida (Hagen)
	b. Labial palps without a large pale, laterodistal spot
	c. Hamules in ventral view each with a posterolateral angulation or process
6a(2b)	a. Lobes of subgenital plate nipple-like, space between apices >2x the basal width of each lobe, each less than 0.2x the length of Ab9 sternum	Leucorrhinia intacta (Hagen)
	b. Middorsal yellow spot on Ab7 about 2x long as wide
6b	a. Lobes of subgenital plate not nipple-like, space between apices no more than the basal width of each lobe, length variable	7
	b. Moddorsal yellow spot on Ab7 about 3x long as wide
7a(6b)	a. Each wing with 2 cell rows for the length of 3 or more cells between veins Rs and Rspl	Leucorrhinia glacialis Hagen
	b. Subgenital plate very small, each lobe < 0.33x as long as wide
7b	a. Each wing with 1 cell row between veins Rs and Rspl, or less often, with 1-2 doubled cells	8
	b. Subgenital plate larger, each lobe at least 0.5x as long as wide
8a(7b)	a. Lobes of subgenital plate contiguous in distal half	Leucorrhinia hudsonica (Selys)
8b	a. Lobes of subgenital plate not contiguous in distal half	9
9a(8b)	a. Lobes of subgenital plate < 1/6 the length of Ab9 sternum, and rounded apically	Leucorrhinia proxima Calvert
	b. Labial palps almost always with a laterodistal pale spot
8b	a. Lobes of subgenital plate at least 1/3 the length of Ab9 sternum, and acute apically	Leucorrhinia frigida (Hagen)
	b. Labial palps without a laterodistal pale spot

Mature Nymphs

1a	a. Ab7-8 with middorsal hooks	2
	b. Abdominal venter without continuous longitudinal dark stripes (transverse bands may be present), usually with 2 or 4 rows of dark oblong spots
1b	a. Ab7-8 without middorsal hooks	4
	b. Abdominal venter with 3 continuous longitudinal dark stripes, although sometimes faint
2a(1b)	a. Frons and occiput usually without dark setal bases, if present few and inconspicuous	Leucorrhinia proxima Calvert
	b. Palpus with few (usually < 12) if any slightly darkened spots on ectal surface
	c. Ab8 middorsal hook length variable, tip usually only slightly beyond base of Ab9 to near (sometime beyond) mid-length
2b	a. Frons and occiput with numerous dark setal bases	3
	a. Palpus with numerous (> 18) conspicuous dark setal bases on ectal surface
	c. Ab8 middorsal hook length variable, tip usually beyond mid-length point of Ab9, sometimes less than mid-length if from a fishless habitat
3a(2b)	a. Antefrons with dark setal bases from anterior portion to about halfway to median ocellus, numbering < 20	Leucorrhinia frigida (Hagen)
	b. Tips of Ab9 posterolateral spines approximately at the same level as paraproct tips (varies by 0.4 mm proximal to 0.4 mm distal to paraproct tips)
	c. Ratio of Ab9 posterolateral spine length : epiproct lenght > 0.7
	d. Ratio of Ab9 posterolateral spine length : Ab9 middorsal length usually > 1.4
3b	a. Antefrons with dark setal bases from anterior portion to median ocellus, numbering > 20	Leucorrhinia intacta (Hagen)
	b. Tips of Ab9 posterolateral spines usually proximal to paraproct tips by 0.7-1.0 mm, appearing about same level as cerci
	c. Ratio of Ab9 posterolateral spine length : epiproct lenght < or = 0.7
	d. Ratio of Ab9 posterolateral spine length : Ab9 middorsal length usually < 1.4
4a(1b)	a. Larger, total length > 16.2 mm (16.2-22.3 mm)	Leucorrhinia glacialis Hagen
	b. Abdominal length = or > 10.6 mm, head length 2.25-2.65 mm, head width 4.75-5.00 mm
	c. Metathoracic femur length 4.2-6.0 mm
	d. Distance between spiniform setae on ligua margin > 2x the setal length
	e. Middorsal hooks on abdomen absent
4b	a. Smaller, total length < 16.3 mm (11.8-16.3 mm)	Leucorrhinia hudsonica (Selys)
	b. Abdominal length = or < 10.5 mm, head length 1.83-2.20 mm, head width 3.90-5.00 mm
	c. Metathoracic femur length 3.0-4.3 mm
	d. Distance between spiniform setae on ligua margin < 2x the setal length
	e. Middorsal hooks on present on Ab3-5 or Ab3-6, sometimes only on Ab3-4 (rarely absent)

Needham JG, Westfall MJ, May ML. 2010. Dragonflies of North America, Third Edition. Scientific Publishers, Gainesville, Florida, USA. xiv + 657 p.
Paulson D. 2011. Dragonflies and damselflies of the East. Princeton Field Guides. Princeton University Press, Pinceton, New Jersey, USA. 538 p.
Tennessen KJ. 2019. Dragonfly nymphs of North America: An Identification Guide. Springer International Publishing, Cham, Switzerland: xiv + 620 p.
Walker EM, Corbet JS. 1975. The Odonata of Canada and Alaska, Vol. 3. University of Toronto Press: Toronto, Ontario. xvi + 308.

Page created: July 17, 1998 - Last updated: April 20, 2020 (EB)