Aquatic Insects of Michigan

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

Toggle Menu

Calopterygidae of Michigan - Identification

[under construction]

Two genera of this primarily tropical family damselflies are found in Michigan. Mature specimens usually are quite large, and the elongate first antennal segment (picture) and large premental cleft (picture) is clearly distinctive from all other damselfly families. Common in streams and rivers, nymphs cling to leafy or woody debris or among aquatic vegetation along accumulating along banks. Adults are noted for their rather large size and beautiful colors. Older literature refers to this family as Agrionidae.

Broad wings, numerous antenodal crossveins between costa and subcosta instead of two, as in other families; dense ventation; postnodal crossveins not in line with veins below them; anal vein at its base is separate from the hind margin of wing, and thus wings are not petiolate; quadrangle is long, nattow, and parallel-sided, with several crossveins; pterostigma poorly developed, without brace vein; males, and often females, pigmented, body color is metallic; nymphs large, long-legged, stiff-looking insects clinging to roots, stems, and other extending substrates at stream edges; head flat, pentagonal, first antennal segment elongate and longer than other six segments combined, often longer than head; prementum produced and having a deep, diamond-shaped cleft; palpal lobes of labium end in 3 curved, acute processes; caudal gills are long and stiff, with long setae, sometimes interspersed with stout spines. Adults with mating behavior involving conspicuous competition among males for territory and females.

References: Tennessen 2006, Walker 1953, Westfall and May 2006

Key to Adults

1a a. Bodies often brilliant metallic green with blue reflections, males with conspicuous dark, broad black bands, or wholely black b. Space proximal to the arculus (median or midbasal space) without crossveins c. Arculus bent where its sectors (M3 and M4) arise, the sectors not proximally curved d. Anterior margin of quadrangle straight Calopteryx, 2
1b a. Bodies not metallic in color, wings pale or hyaline, males with conspicuous red basal spot b. Space proximal to the arculus with several crossveins c. Arculus not bent where its sectors arise, the sectors proximally curved d. Anterior margin of quadrangle convex Hetaerina

2a(1a) a. Wings mostly or entirely dark brown, length of wings about 3x their greatest width Calopteryx maculata (Beauvoix)
2b a. Wings mostly hyaline or only slightly smoky, with an apical dark brown band Calopteryx aequabilis Say

3a(1b) a. Ab2-3 sterna modified with secondary genitalia, markedly different in shape from remaining segments Males 4
3b a. Ab2-3 unmodified and not markedly different from other abdominal segments Females 5

4a(3b) a. Basal spot of forewing usually bright red, that of hindwing much duller red or brown b. Paraprocts in lateral view curving strongly upward, in ventral view fairly straight and generally convergent throughout their length Hetaerina titia (Drury)
4b a. Basal spots of both pairs of wings largely bright red, rest of wings hyaline or smoky, not dark brown b. Paraprocts in lateral view not curving strongly upward, in ventral view distinctly concave on inner side and not convergent throughout their length Hetaerina americana (Fabricius)

5a(3b) a. Dorsal carina of Ab10 usually terminating in a prominent spine that projects beyond every point of the apical margin of the segment b. Wings usually uniformly tinted, or darker apically than basally Hetaerina titia (Drury)
5b a. Dorsal carina of Ab10 usually not terminating in a prominent spine, although a small one may be present b. Wings darker basally than apically, often nearly hyaline beyond the nodus, never uniformly dark Hetaerina americana (Fabricius)

Key to Mature Nymphs

1a a. Prementum cleft long, nearly halfway to its base b. Posterolateral margins of Ab9-10 without spines Calopteryx, 2
1b a. Prementum cleft shorter, reaching only to base of palpal lobes b. Posterolateral margins of Ab9-0 with small, distinct spines Hetaerina, 3

2a(1a) a. Ant1 shorter, no longer than 0.85x the greatest width of head across the eyes b. Tubercles behind eyes prominent and acute, raised above level of eyes c. Hind femur of final instar 7.5mm or less Calopteryx maculata (Beauvoix)
2b a. Ant1 longer, 0.95x or more the greatest width of head across the eyes b. Tubercles behind eyes low and rounded, not raised above level of eyes c. Hind femur of final instar 8.2mm or longer Calopteryx aequabilis Say

3a(1b) a. Ab8 with lateral spines b. Gills distinctly banded Hetaerina titia (Drury)
3b a. Ab8 without lateral spines b. Gils not distinctly banded, distinct markings restricted to margins Hetaerina americana (Fabricius)

Page last edited: February 9, 2017 (EB)