FAMILIES OF ODONATA OF BRITISH COLUMBIA

by
R. A. Cannings and G. G. E. Scudder 
Copyright © 2005 - All rights reserved

Key to Families of Odonata

1. Forewings and hindwings similar in shape and form; when at rest wings held vertically above the body; males with 2 superior and 2 inferior anal appendages; females with an ovipositor (Suborder Zygoptera) ..................2

- Forewings and hindwings not exactly similar in shape and form, but hindwings much broader near base than forewings; when at rest wings held horizontal; males with 2 superior and 1 inferior anal appendage; females with or without an ovipositor (Suborder Anigoptera)............................................................... 4

2. Antenodal crossveins numerous; postnodal crossveins not in line with veins below them; anal vein at the base separate from posterior margin of wing; quadrangle with several crossveins........................................................... Calopterygidae

- Wings with only 2 antenodal crossveins; postnodal crossveins in line with veins below them; anal vein joined with posterior margin of wing for a distance from the wing base; quadrangle without crossveins............................................. 3

3. Wings with R₄₊₅ arising from R_s nearer to the arculus than to the Nodus............................................................................................. Lestidae

- Wings with R₄₊₅ arising from R_s nearer to the nodus than to the arculus .............................................................................................Coenagrionidae

4. Forewing with triangle more distant from the arculus than in the hindwing.......... 5

- Forewing and hindwing with triangle about the same distance from the arculus ...................................................................................................................7

5. Wings with anal loop short and wide, and without a mid-vein; hindwing with triangle distant from the arculus................................................... Macromiidae

- Wings with anal loop long and with two rows of cells separated by a mid-vein; hindwing with triangle touching the arculus.................................................. 6

6. Wings with R_s and MA distinctly separate beyond the arculus; body usually metallic .................................................................................... Corduliidae

- Wings with R_s and MA fused for a little way beyond the arculus; body not metallic
..................................................................................................Libellulidae

7. Head with eyes contiguous dorsally.................................................................. 8

- Head with eyes widely separated dorsally.......................................................... 9

8. Head with eyes contiguous at a single point dorsally................... Cordulegastridae

- Head with eyes contiguous along much of length dorsally....................... Aeshnidae

9. Wings with pterostigma widened near middle and shorter than half the distance from the nodus to the inner edge of the pterostigma....................... Gomphidae

- Wings with pterostigma not widened near middle, but longer than half distance from nodus to the inner edge of the pterostigma ....................................Petaluridae

Description of Families

Suborder Zygoptera (damselflies)

Family Calopterygidae (jewelwings)

The large-bodied adults (43-54 mm long) are metallic green (females) or blue-green (males) with black-tipped, densely veined wings. They fly with a beautiful dancing flight along clear streams, where the larvae cling to submerged vegetation. The long-legged, stiff larvae can be distinguished by their long antennae -- the first segment is longer than all the others combined.

In British Columbia, Calopteryx aequabilis Say is the sole representative of the Calopterigydae, a family of elegant and colourful damselflies (the family name means “beautiful wings”). The only known population of this rare species lives in the outlet stream of Christina Lake, east of Grand Forks.

Family Coenagrionidae (pond damsels)

In British Columbia the Coenagrionidae consists of 6 genera and 18 species. The adults are frequently blue marked with black, but the ground colour may be green, yellow, orange, red or purple. There are often two female colour forms, one of which is similar to the male. Eggs are laid in the tissues of water plants and females may completely submerge for considerable periods during oviposition. The larvae are less elongate and have shorter labia than those of the Lestidae. The genera most often encountered are Enallagma and Ischnura. Enallagma, the common genus of blue and black damselflies, contains seven species in the province. E. boreale Selys and E. cyathigerum (Charpentier) are the most widespread species; the former fairly swarms around the kettle lakes of the central plateau; the latter is the only Holarctic member of the genus and family. E. clausum Morse is typical of alkaline ponds and is the only species of the seven restricted to western North America.

Ischnura is a cosmopolitan genus whose distribution in North America is decidedly southern in character. Two species, I. cervula Selys and I. perparva Selys are widespread and common in Typha and Scirpus marshes in the south. The male of the latter (23-28 mm long) is the smallest damselfly in the province. A third species, I. erratica Calvert, is restricted to the south coastal region, and I. damula Calvert is known only from Liard River Hot Springs in the far northeast. Coenagrion is a predominantly Old World genus with three species ranging across most of boreal North America; C. interrogatum (Hagen) and C. resolutum (Hagen) occur in most of the province, C. angulatum Walker only east of the Rocky Mountains. The two western Canadian species of Argia are of special. Both Argia emma Kennedy and A. vivida Hagen live in streams, a rather unusual habitat for the Zygoptera of the region. A. emma also develops along lakeshores in southern valleys, and A. vivida is scattered here and there, mostly in the warm rivulets flowing from thermal springs. Both are considered threatened. At 33-40 mm long, A. emma is the largest coenagriid in the province. Amphiagrion abbreviatum (Selys) and Nehalennia irene (Hagen) are the sole representatives of their genera in the province. The former is a red and black species inhabiting springs and seeps in the southern valleys; the latter is a tiny blue and metallic green denizen of sedge marshes.

Family Lestidae (spreadwings)

The Lestidae, or spreadwing damselflies, is one of only two cosmopolitan genera of Zygoptera. It is a small, but widely distributed family in British Columbia, and there contains only one genus, Lestes, with five species. Most are widespread within North America and the province. In British Columbia, adults range in length from 30 to 45 mm; they are metallic green or bronze, but parts of the body become pruinose-grey with age. They characteristically perch with wings half-spread. Females oviposit in tandem with males and eggs are usually placed in plants above the surface of the water. Larvae have unusually elongate labia and long, broadly banded gills. Some species are adapted to living in temporary ponds; in these situations larvae grow rapidly after overwintering as eggs. Lestes dryas Kirby, a bright metallic green species, is the only member of the family that lives in both North America and Eurasia. Of the three most common BC species, it emerges first, in late spring and early summer. L. disjunctus Selys emerges next, and L. congener Hagen is the last to appear.

Suborder Anisoptera

Family Aeshnidae (darners)

In British Columbia, the Aeshnidae are large (53-84 mm long), swiftly flying dragonflies, usually marked with blue, green or yellow, and represented by two genera, Aeshna, with 13 species and Anax, with one. Adults tirelessly hunt for insects over ponds, lakes and streams, and wander widely in search of prey. When they land, most species hang vertically. Females oviposit in water plants or floating wood above or below the water line. The larvae are slender and sleek, with flattened labia lacking setae. They are rapacious hunters among water plants.

Six of the 13 Aeshna species are boreal (A. juncea (Linnaeus) and A. subarctica Walker are Holarctic) and four others are transcontinental south of the boreal forests. Three are strictly western in range, including the common A. palmata Hagen and A. multicolor Hagen. A. subarctica, A. sitchensis Hagen, A. septentrionalis Burmeister and A. tuberculifera Walker are peatland obligates in the province. A. interrupta Walker is one of the most widespread species in the area and is found in many habitats from northern peatlands to temporary ponds. It is the characteristic species of grassland ponds. A. constricta Say is an uncommon species typical of small ponds in the south; its preference for these habitats, often threatened by human development, place it on the vulnerable list. Along with A. tuberculifera, the females mimic males in coloration and behaviour; they are also the only species of the genus in our region that regularly lay their eggs above the water in emergent vegetation. A. californica Calvert is remarkable for its springtime flight season. In the south, it may appear as early as the last week of April, emerging with the earliest dragonflies. A species of lowland ponds, it normally disappears by early August, just when many darner species are reaching their peak abundance. Anax junius (Drury) the Green Darner, has a southern transcontinental distribution. At least some populations appear to migrate, with spring immigrants moving north in the spring and their offspring flying south in August and September. Other populations are resident.

 

Family Cordulegastridae (spiketails)

Cordulegaster dorsalis Hagen is the only representative of the Cordulegastridae in British Columbia. It is a large (70-85 mm long), black and yellow dragonfly, most common on coastal streams, but it is also a rare inhabitant of small streams, especially spring-fed ones, in the southern Interior of the province, especially in the Columbia-Kootenay region. Adults patrol these streams, and the female, hovering in a vertical position, shoves eggs into the sand and silt of the streambed with her spade-like ovipositor. The large, squat, hairy larvae bury themselves in the sediment to await their prey. The labium of the larva, with its palps deeply and irregularly toothed, is distinctive.

 

Family Corduliidae (emeralds)

In British Columbia the Corduliidae is a family best seen around lakes, boggy streams and peatlands in the mountains or in the north. Eleven of 15 species are boreal in distribution. The adults are medium-sized dragonflies (39-63 mm long), usually with metallic blackish green or brassy bodies and bright green eyes. There are three genera in the province. Cordulia shurtleffi Scudder is the commonest member of the family, often abundant in peatlands and along the shores of mountain lakes in early summer. The two Epitheca species, E. canis MacLachlan and E. spinigera (Selys),are brown, rather setose dragonflies with blue-grey eyes. They are transcontinental in the Transition forests south of the boreal zone and lay long strands of eggs, sometimes communally, along lakeshores. Somatochlora is the predominant genus with 12 species. Somatochlora albicincta (Burmeister) and S. cingulata (Selys) are lake dwellers; S. hudsonica (Selys) and S. semicircularis (Selys) live in sedge marshes (the latter is the only species in the family restricted to the western mountains); S. minor Calvert and S. walshii (Scudder) inhabit forest and peatland streams; S. brevicincta Robert, S. franklini Selys , S. forcipata (Scudder), S. kennedyi Walker, S. septentrionalis (Hagen) and S. whitehousei Walker are peatland inhabitants.

 

Family Gomphidae (clubtails)

The Gomphidae is a large family that is poorly represented in British Columbia; species live mostly in relatively warm streams, and the mountain-fed waters of the province are too cold for a diverse fauna. Only six species in four genera occur, but they are not common. Gomphids are medium-sized dragonflies (44-57 mm long) readily recognized by their widely separated eyes and their green or yellow bodies striped in brown and black. They frequently rest horizontally on the ground. The female lacks an ovipositor and drops the eggs directly into clear streams and along the sandy shores of larger lakes. The rather flattened larvae burrow in the bottom sediments.

Gomphus graslinellus Walsh lives along valley bottom lakeshores in the Okanagan, Shuswap, and Boundary regions, the only part of its Canadian range west of Manitoba. The larvae burrow in the sand and silt along wave-washed shores and the adults bask on the warm beaches. Stylurus olivaceus (Selys) is closely related and has similar habits and distribution, although it also inhabits the larger, warm rivers such as the Okanagan and Thompson. Ophiogomphus colubrinus Selys is a boreal species, found in northern streams. O. occidentis Hagen and O. severus Hagen are more widespread species that live in both lakes and streams. The former is restricted to lowland areas south of 51°N, but the latter ranges north well into the boreal forest. Octogomphus specularis (Hagen), the only species in the genus, lives in coastal streams from the Fraser Valley south to Baja California.

 

Family Libellulidae (skimmers)

The Libellulidae is the largest dragonfly family in the province, containing seven genera and 25 species. The adults are most common around ponds, marshy lakeshores and sluggish streams where the adults dart about and spend much time perched horizontally in the sun. Females oviposit alone or in the company of guarding males and, lacking piercing ovipositors, dip the abdomen in the water, releasing the eggs. The larvae, like those of the Corduliidae, move sluggishly through aquatic vegetation or squat on the bottom mud.

Leucorrhinia species are small, black, white-faced dragonflies marked with red or yellow. Five of the six species are boreal and are most prevalent in the mountains or in the north around the marshy shores of lakes in the late spring or early summer. The tiny L. patricia Walker is rare, known from only a few peatland ponds where the larvae live in aquatic moss mats; it is the smallest (24-29 mm long) species of British Columbia Libellulidae. L. intacta (Hagen) is the anomaly in the genus, preferring cattail marshes in warm valley bottoms. The genus Libellula contains five large, striking species in British Columbia; most have banded or spotted wings, and in most species, the males sport white, pruinose abdomens. L. quadrimaculata Linnnaeus, one of the most widespread dragonflies on the globe, is everywhere, from northern bogs to alkaline ponds. L. pulchella Drury, the largest libellulid in the province (49-57 mm long), is boldly patterned in white and dark brown; it lives only in the warmest parts of the southern Interior valleys. Most of this species' habitat has been drained and filled in the past century.

Sympetrum species are mostly small red dragonflies abundant as adults in the late summer and fall. The nine species are especially common in marshy lowland habitats. Unusual in the genus, the colour of S. danae (Sulzer) is black and yellow. This species has a wide ecological tolerance, being equally at home in northern and mountain peatlands and in hot, lowland marshes. S. vicinum (Hagen) is rare in the province, and therefore on the list of species of management concern. It flies late, well into November in mild autumns along the south coast and in the southern Okanagan Valley. S. costiferum (Hagen) and S. corruptum (Hagen) are typical of saline ponds in Interior grasslands and, along with the latter, S. madidum (Hagen) and S. pallipes (Hagen) can develop in ephemeral ponds.

The mature males of both Pachydiplax longipennis (Burmeister) and Erythemis collocata (Hagen) are a distinctive chalky blue colour, covered with pruinosity. The young males and females of the latter specie are bright green. Pachydiplax perches conspicuously on vegetation; Erythemis rests on the ground. Both species are rather common on southern Vancouver Island, less so on the adjacent mainland, and rare in the southern Okanagan.

With their broad hindwings and gliding flight, Tramea lacerata Hagen and Pantala hymenaea (Say) frequently travel widely. Both species have shown up in the Victoria area, presumably visitors from the south, but nether species is known to breed in the province.

 

Family Macromiidae (cruisers)

The Macromiidae are large (64-74 mm long) yellow and black dragonflies inhabiting the rivers and wave-washed shores of lakes, where the adults fly rapidly out over the water. The thorax is encircled between the wings by a distinctive, oblique yellow band. The larvae sprawl on the bottom silt and sand. Their long spider-like legs and the horn-like projection between the eyes are characteristic. The single genus in British Columbia, Macromia, contains one species, M. magnifica MacLachlan. In the southern, dry valleys of the Interior, such as the Okanagan, specimens are pale, with much yellow on the body; in the wetter Shuswap region (and in the coastal forests of the Fraser Valley), the dragonflies are darker. This dark form was described as M. rickeri Walker, but is considered by most workers to be conspecific with M. magnifica.

Family Petaluridae (petaltails)

The ancient dragonflies of the Petaluridae flourished in the Jurassic Period at least 150 million years ago, well before the land now known as British Columbia existed. Today, relict populations persist in mountain swamps and seeps in widely scattered regions -- New Zealand, Australia, Chile, Japan, the Appalachian Mountains, and western North America. The latter species, Tanypteryx hageni (Selys), ranges from California north along the Cascades and Coast Mountains to the north coast of British Columbia. The black adult (53-59 mm long) is spotted with yellow and has widely separated eyes. The female has an ovipositor, but merely inserts her eggs among the wet moss in mountain and coastal seeps.

The larva is unlike that of any of our other dragonflies -- it is amphibious. It digs a burrow in the mud and moss saturated by the trickling spring water. Dozens of burrows can be concentrated in a small area. The larvae are mostly nocturnal, coming to the burrow entrance to await their prey. They can breathe air for long periods and often forage well out of the water-filled burrow. Tanypteryx is seldom seen in British Columbia; larvae are known from only one site near Vancouver.