Introduction

INTRODUCTION

Dragonflies and dam- wing is fully functional and independently mov- selflies make up the able. The robust thorax is strikingly skewed, forcing insect order Odonata. the legs forward and the wings backward. They are found worldwide, except for Antarctica. Even the most casual observer must appreciate Most treatments recognize three suborders within the phenomenal agility that odonates display in the Odonata. The names of these groups derive flight. Throughout human history they seem to from the relative shapes of the fore- and hindwings. have spawned not only interest but also fear. Their The dragonflies belong to the suborder Anisoptera, large size and fast, buzzing flight are the basis for the hindwings of which are broader than the such names as “devil’s darning needles” and “horse forewings. The damselflies, suborder Zygoptera, stingers.” Although some of the larger dragonflies have fore- and hindwings of the same shape. The can pinch a finger placed in the mouthparts, odo- members of a third suborder, the Anisozygoptera, nates do not normally bite humans. These names are often called “living fossils” and can be recog- may have originated in part from occasional in- nized by a mix of the characters seen in the Aniso- stances in which a female dragonfly mistakes the leg ptera and Zygoptera. This group contains only two of a wader or river rafter for a plant when laying her extant species, both restricted to East Asia. In most eggs. Though I have never experienced this first- parts of the world the term “dragonfly” refers to hand, those that have confirm that having a drag- members of any of the three suborders, but in North onfly attempt to lay eggs in you is painful! America the term usually refers specifically to mem- Not only are odonates among the most beautiful bers of the Anisoptera. In this book I will refer to of insects, they are also beneficial. Both dragonflies dragonflies and damselflies collectively as Odonata and damselflies are voracious predators, both as or odonates. aquatic larvae and as adults, and one of their main Because odonates are remarkably distinctive in prey items is mosquitoes. appearance, and unique in many other aspects of their biology, they are seldom mistaken for other insects. Some 5,500 species are known worldwide, just Habitats and Zoogeography of the 433 of them in North America north of Mexico. South-Central United States Odonata, especially in the tropics, is one of the larger aquatic insect orders, giving its members, wher- The south-central United States, as defined herein, ever they occur, an ecologically important role in includes Texas and its four surrounding states. The aquatic ecosystems. (Other insects that spend a sub- area covered is approximately 1.2 million km2, of stantial period of their life in the water include which 695,000 km2 are in Texas. The region encom- mayflies, order Ephemeroptera, and stoneflies, or- passes ten biotic provinces (Fig. 1). The Mississippi der Plecoptera.) River forms the eastern boundary of the region The Odonata represent one of the most primitive (which means that the few parishes of Louisiana living insect groups. The earliest fossil odonates are that lie east of the Mississippi are not covered), and some 250 million years old. Members of the order the Apachian and Navahonian biotic provinces Protodonata, the probable ancestors of Odonata, bound the western edge. lived more than 300 million years ago, and some A considerable amount of work has been done had wingspans greater than 71 cm (2 feet)! The clos- on the distribution of vegetation types in Texas est living relatives of the Odonata are the mayflies. (Bray 1901, 1905; Carter 1931; Tharp 1926, 1939), Odonates exhibit many primitive features, includ- Louisiana (Viosca 1933; Holland 1944), Arkansas ing the inability to fold their wings flat and fanlike (Turner 1935; Stroud & Hanson 1981), and Okla- over the abdomen, a trait they share with the homa (Ortenburger 1928a,b; Bruner 1931). There is mayflies. The wings have dense venation, and each a tremendous variety in the environments available

Coloradan Carolinian Navahonian Kansan Texan

Austroriparian

Apachian Chihuahuan Balconian

Tamaulipan

Fig. 1. The ten natural biotic provinces of the south-central United States (modified from Blair 1950, Dice 1943, Blair & Hubbell 1938). for plant and animal communities, which are deter- handle, resulting in a shorter growing season in the mined largely by climatic conditions and topogra- latter. Major vegetation types include eastern pines phy. A north–south line passing through central and hardwoods, central prairies and grasslands, Oklahoma and Texas divides our region into areas western semidesert areas, and western montane for- of moisture sufficiency and moisture deficiency ests. Elevation ranges from sea level along the (Blair 1950), thus dictating plant and animal distri- coastal areas to 4,011 m (Wheeler Peak, Taos Coun- butions in the region. Cope (1880) recognized three ty, New Mexico) in the Carson National Forest. The major biotas in Texas: a Sonoran fauna, an Austror- major watersheds in the region (Fig. 2) drain in an iparian fauna, and a Neotropical fauna. I recognize eastward or southeastward direction, and nearly all a further division into ten distinct regional biotic of them enter or approach the Austroriparian prov- provinces, as outlined by Blair and Hubbell (1938), ince. These stream systems provide important dis- Dice (1943), and Blair (1950), and as shown in Fig. persal routes for the westward distribution of species 1. These provinces, which differ in topography, an- of the Austroriparian province into the more arid, nual temperature range, vegetation, soil type, ge- treeless environments (Blair 1950). ology, and climate, have been given the names The Austroriparian province, as defined by Dice Apachian, Austroriparian, Balconian, Carolinian, Chi- (1943), encompasses the Gulf coastal plain from ex- huahuan, Coloradan, Kansan, Navahonian, Tamau- treme east Texas to the Atlantic Ocean. This biotic lipan, and Texan. The provinces are useful in detail- region’s western boundary is demarcated by the ing the distribution of Odonata, biologically vs. availability of moisture. The typical vegetation politically, within our region, as you will see in the types include longleaf pine (Pinus palustris) and individual species accounts. loblolly pine (P. taeda) and hardwood forests vari- Mean annual precipitation ranges from 147 cm/yr ously consisting of sweetgum (Liquidambar styraci- in the moist eastern parts of the region, such as New flua), post oak (Quercus stellata), and blackjack oak Orleans, to less than 25 cm/yr in the arid western (Q. marilandica). The lowland hardwood forests of areas, such as El Paso. Most of the precipitation falls the southeastern portion of this province are typi- during the months of March to May. Temperature is cally characterized by magnolia (Magnolia grandiflo- also an important factor in dictating the distribution ra), tupelo (Nyssa sylvatica), and water oak (Q. nigra) of plant and animal communities, and ranges from in addition to those trees mentioned above. Other an annual average of 22.8° C ( 73.4° F) in subtropical plants typical of this region include Spanish moss Brownsville, Texas, to 12° C (53° F) in the Texas pan- (Tillandsia usneoides) and palmetto (Sabal minor).

Colorado (NM) St. Francis Cimarron White Canadian Arkansas

Red Ouachita Bayou Pecos Bartholomew Upper Rio Brazos Trinity Sabine Grande Mississippi Colorado Neches

Nueces San Jacinto Guadalupe Lower San Antonio Rio Grande

Fig. 2. The natural watersheds of the south-central United States.

The Texan biotic province constitutes a broad For the Kansan province, I follow Blair (1950), ecotone between the forests of the Austroriparian who delineated the province differently than did province in the eastern portion of this region and Dice (1943). Dice limited the province, excluding the western grasslands. The Balcones Escarpment the Permian redbeds, while Blair included the areas forms an abrupt boundary to the west, otherwise north of the Edwards Plateau and south of the Red delineated by a line based on soil type. This area was River. The province is characterized by a mixture of once characterized by tall-grass prairies supported eastern forest species and western grassland species. by clay soils, but cultivation of much of the area has Notable exceptions to the monotonous prairies of led to sandy soils characterized by combination this province are Palo Duro Canyon State Park and oak-hickory forests, dominated usually by post and Caprock Canyon State Park, which have been char- blackjack oaks and hickory (Carya texana). Thornth- acterized as relict habitats. Moisture decreases from waite (1948) classified this province as having a east to west in this province, and Thornthwaite moist, humid climate, but receiving little water be- (1948) considered the region moisture-deficient. yond that required for growth. The drainage pattern The Balconian biotic province is defined by the of the Texan province is an important biogeograph- Edwards Plateau of Texas and derives its name ical feature (Blair 1950). The Red and Trinity rivers, from the Balcones fault zone that forms its south- along with their tributaries, drain the northern part ern and eastern boundaries (Blair 1950). It is char- of this province. Both of these rivers enter the Aus- acterized by scrub forests of juniper (Juniperus spp.) troriparian province before emptying into the Gulf. and oaks (Quercus spp.), including stunted live oak The southern portion of this province is drained (Q. virginiana). largely by the Brazos, Colorado, San Marcos, and Farther south, the Tamaulipan province extends Guadalupe rivers. from southern Texas into eastern Mexico. This One of the unique features in this province is the semiarid region is dominated by mesquite (Prosopis Arbuckle Mountains in south-central Oklahoma, glandulosa), Acacia spp., Mimosa spp., and prickly just north of the Red River. This area is dominated pear cactus (Opuntia spp.). Thornthwaite (1948) by granite and travertine limestone geologic forma- noted a marked deficiency of moisture for plant tions. One of the most prominent of these forma- growth, though some growth occurs year round. tions is in Turner Falls Park near Davis, Murray This province is drained in the north largely by the County, Oklahoma. Within the park, there is a 25 m Nueces River and its tributaries, and is poorly waterfall on Honey Creek. drained in the southern portion by minor tributar-

For general queries, contact [email protected] © Copyright, Princeton University Press. No part of this book may be distributed, posted, or reproduced in any form by digital or mechanical means without prior written permission of the publisher. 4 INTRODUCTION ies of the Rio Grande. In the Brownsville region, to sionally males of other species. At some point a re- the south, the province becomes subtropical. ceptive female looking for suitable egg-laying areas The Chihuahuan province includes the Trans- is seized by the male. This capture usually takes Pecos area of Texas, excluding the Guadalupe place in midair, the male flying over the female and Mountains. It extends southward into the Mexican grabbing her head and thorax with his legs. In dam- states of Chihuahua and Coahuila and is drained selflies, the male grasps the female’s prothorax (the largely by the Rio Grande. This biotic province is segment of the thorax behind the head) with the more diverse in physiographic features than all oth- clasping structures at the tip of his abdomen (this is ers in the region (Blair 1950). The climate in this the tandem position). area is arid and moisture-deficient (Thornthwaite In dragonflies he grasps her head, and in aged fe- 1948), and the vegetation is variable, but basin areas males of some larger species (darners) the resulting up to 1,500 m in elevation include grasses, desert damage to the eyes is often noticeable. The male shrubs, and creosote bush (Larrea tridentata). will then curl his abdomen around so that sperm Streams in this area are usually small and intermit- can be transferred from the genital pore on the ven- tent; those that are permanent are usually spring- tral side of his segment 9 to the accessory genitalia fed. The various mountains, including the Chisos located on the ventral side of his segment 2. This and Davis ranges, show a vertical zonation of plant usually happens quickly, and the male then communities, with elevations above 1,500 m domi- straightens his abdomen so that the receptive fe- nated by Emory oak (Quercus emoryi) and cedars male can curl her abdomen around, such that her (Juniperus spp.). genital opening on the ventral side of segment 8 is The Navahonian province includes most of New in contact with his accessory genitalia on segment Mexico and barely enters the northern edge of west- 2. It is not unusual to see odonates in this wheel ern Texas (Culberson County) at the southern ex- position. They may remain in this position, usual- tension of the Guadalupe Mountains. A vertical ly protected within vegetation, for minutes or zonation in elevation similar to that of the Chihua- hours, depending on the species. Still others copu- huan province characterizes this area. Trees domi- late while in flight. (A number of the color photos nant at elevations above 2,500 m include various in this book are of mating pairs.) Females will mate pines (Pinus spp.), oaks (Quercus spp.), and Douglas more than once, and in at least some species, males Fir (Pseudotsuga menziesii). are known to remove the sperm from previous Small portions of the Carolinian (northern males before mating. Arkansas), Coloradan (northwestern New Mexico), and Apachian (southwestern New Mexico) prov- Egg-laying inces are also found within the region covered by Female damselflies, petaltails, and darners all lay this book. These peripheral provinces are home to their rod-shaped eggs using a specialized structure several odonates whose ranges barely extend into called the ovipositor. They use the bladelike struc- the south-central United States. tures of their ovipositor to make slits in the soft tis- sues of plant stems, where they then lay their eggs. These eggs may be laid above, at, or below the water Life History of Odonata line. In other odonate families the eggs are generally more round in shape and often have a gelatinous As is true of any living organism, reproduction is a covering. These eggs are laid in or near water or in critical stage in the life cycle of odonates. It may an area that will fill with water. Female Spiketails take an individual adult anywhere from a day to employ a specialized ovipositor in sewing-machine several weeks, depending on the species, tempera- fashion to deposit eggs in the substrate of shallow ture, availability of food, and other environmental streams. The eggs will generally hatch in about a factors, to become sexually mature. Upon maturity, week. Eggs laid in temporary pools, however, will the male will, in most species, patrol a territory he hatch more quickly, whereas others may be delayed has established over and around water. The male for months. The male may continue to grasp the fe- will search for females in this territory, and will de- male (in the tandem position) while she lays eggs, fend it against other males of his species and occa- or he may release her, but he will remain hovering

a b

c d

Fig. 3. Odonata larvae: (A) Great Spreadwing (Archilestes Blue Dasher (Pachydiplax longipennis); (D) Skimmer grandis); (B) Common Green Darner (Anax junius); (C) (Libellulidae).

Damselfly larvae have three leaflike gills at the some cases even across oceans, on the wings of pre- tip of the abdomen. Although the gills are used in vailing wind currents. respiration, they are also used like fins for swim- ming. Larvae have the ability to regenerate these gills, at least in part. Damselfly larvae also have the Seasonality of Odonata in the South-Central ability to absorb oxygen through the wall of their United States rectum. Dragonfly larvae lack the terminal gills and absorb oxygen through internal rectal gills instead. The flight season of most species of Odonata in this region extends from the spring through the sum- Adults mer months, and occasionally persists into the fall. An odonate larva will typically climb out of the wa- The onset and duration of emergence, however, are ter onto an emergent piece of vegetation, bridge py- both variable. Many species of temperate origin lon, or similar structure to begin its adult emer- (e.g., Attenuated Bluet, Springtime Darner, Harle- gence. Some species are known to walk considerable quin Darner, Banner Clubtail, Twin-spotted Spike- horizontal distances (30 m) and heights (10 m) tail, Stream Cruiser, Blue Corporal) have early from the body of water in which they developed. (March–May) and explosive emergences in this area Emergence generally occurs at night or in the early and then soon disappear. In the southern portions morning, under the cover of darkness. Clubtails and of the region, the year-round temperatures, averag- damselflies, however, often emerge during the day. ing 23° C (73° F), and the subtropical climate allow A split develops along the dorsal side of the head several species to fly year round. Fifteen species (in- and thorax as the larval skin dries. The adult will cluding Familiar Bluet, Fragile Forktail, Common then start to pull itself free from the old larval ex- Green Darner, Eastern Pondhawk) have been en- oskeleton, or exuviae (see photo 48f). This process countered as adults in every month. Other species may take some time, since the legs have to harden (Fine-lined Emerald and Blue-faced Meadowhawk) before it can pull itself completely free. Once it has are seen flying only later in the year. Because of the done so, it will remain hanging from its perch until latitudinal gradient in temperature seen in the re- its wings have been inflated (via the veins) and the gion, emergence occurs one to several weeks later in body has begun to harden. This newly emerged, or the more northern areas than in the subtropical teneral, adult will not have the bright vibrant colors southern areas. of its mature counterpart; the wings will appear Damselflies generally emerge as soon as tempera- cloudy or have a shimmer to them, and the tenerals tures permit in the spring, and continue to emerge are vulnerable during this time of limited mobility. throughout much of the summer. This results in a Although they can fly, almost immediately, they heterogeneous age structure, often allowing more usually do so only when disturbed. It may take sev- than one generation per year. Many of the smaller eral days or more than a week before sexual maturi- pond damsels, for example forktails, have multiple ty is reached. During this time most odonates re- (two or three) generations per year. The larger pond main away from the water. Males usually mature damsels, the spreadwings, and the broad-winged more quickly than females and make their way back damsels generally require a full year for development. to suitable egg-laying habitats, where they set up Many dragonflies differ from damselflies in hav- territories and wait for females. ing an obligate larval diapause (a required period of Odonates of a number of species are crepuscu- arrested development), followed by a synchronous lar: they feed actively at dusk. Occasionally, a spring or early-summer emergence. This pattern re- dragonfly or damselfly will come to a light at sults in a homogeneous age structure and a sudden night, but most of these are individuals roosting disappearance later in the summer or fall. Most spe- nearby and not actively flying. Odonates of some cies require at least a year to develop, and some, for species, however, like the shadowdragons, may ac- example spiketails, require longer (several years). A tually be nocturnal. more or less typical adult lifespan, barring predation Dragonflies typically have no reason to fly great or other calamity, might be three months. distances, but because they are accomplished glid- Development time is generally longer for those ers, they are quite capable of sustained flight, in species restricted to running-water situations than it

For general queries, contact [email protected] © Copyright, Princeton University Press. No part of this book may be distributed, posted, or reproduced in any form by digital or mechanical means without prior written permission of the publisher. INTRODUCTION 7 is for those found in ponds or lakes. A general sea- however, such as allowing livestock access to these sonal progression, with the peak months in June areas, can severely impact these pond species. and July, as seen for the entire south-central United The single most important factor in the conser- States, was observed by Bick (1957) in Louisiana. vation of Odonata is the protection of land and Species present early in the year (January–February) aquatic habitats. The efforts needed for the protec- were also generally present later in the year tion of these resources vary with the type of habitat. (November–December). Removing the surrounding vegetation from streams by mowing will completely alter the composition of the water, effectively removing some species. A Conservation buffer zone of vegetation on either side of a stream (generally, at least 30 m is recommended) helps to Odonates play a major beneficial role as predators of prevent erosion. Construction of dams poses a real mosquitoes and other biting insects, both as adults challenge to stream species. In all of Texas there is and as immatures. The larvae also form an impor- now only one natural lake (Caddo Lake), which in- tant link in food chains for fish and other aquatic dicates just how prevalent dams are in the state. The vertebrates. Historically, the Odonata have not been numerous manmade reservoirs may provide habitat acknowledged as good indicators of water quality, for those few species that can breed in lakes, but but numerous authors (Castella 1987; Dolny & they deprive other odonates of habitat. Rivers are Asmera 1989; Bulankova 1997; Chovanec & Raab seldom protected from human impact and distur- 1997) have recognized that capacity in this group bances, but groups in areas like the Big Thicket Na- recently. Schmidt (1985) presented a convenient tional Preserve in east Texas are working hard to se- working scheme for the rapid evaluation and char- cure these areas by purchasing riparian lands and acterization of aquatic habitats. creating corridors between their preserve units. The most recent estimates (Dunkle 1995) are that For some species, especially those living in more about 15% of the dragonfly species and 6% of the arid conditions, a small area of suitable habitat may damselfly species in North America have limited or be all that is needed for their continued existence. restricted geographic ranges and may be at risk of For most species, however, larger areas of suitable extinction. Areas of particularly high endemism in habitat are necessary. This is where a good network the United States include the New England coast, of local, state, and national parks is so important. Florida, the central Gulf of Mexico coast, and the Though such areas provide protected habitats for Pacific Coast. A few species, the Oklahoma and odonates, on the whole they protect relatively little Ozark Clubtails and the Texas Emerald, for example, land. Private groups like the Nature Conservancy are endemic to smaller regions within the south- are crucial for securing and protecting land. Time is central United States. Those species living in of the essence, for whereas observations have streams, rivers, and other flowing-water habitats are shown some species expanding their ranges because at greatest risk. of global warming, many others are left to compete Sewage and other organic wastes run off into for fewer habitats of poorer quality. streams and promote bacterial growth that depletes Collecting odonates on these protected lands re- the oxygen content of the water and in turn stress- quires special permission and often a scientific col- es or kills odonate larvae. Fertilizer runoff from agri- lecting permit. I have found that land stewards or cultural fields leads to eutrophication, promoting agencies in charge of these protected areas generally algal growth that may lead to blooms removing have no problem with the collection of the voucher oxygen from the system and preventing sunlight specimens needed to ensure proper documentation from penetrating the water. Pesticide runoff also and identification. Often they encourage this prac- kills larvae. Those species of Odonata living in tice in order to ensure that the fauna of the lands ponds and lakes are generally at less risk. In fact, hu- they manage and protect are properly documented. man activities resulting in the construction of new In Texas, like most other states, scientific collecting ponds, lakes, borrow pits, and even stock tanks may permits are required for any state park property or provide some Odonata with a new habitat, lacking preserve, and are administered through a central competition, to colonize. Other human activities, agency (Texas Parks and Wildlife). Because National

Parks administer their own scientific collecting per- and ponds (Dig a Pond for Dragonflies and Managing mits, each park must be contacted separately. In my Habitats for Dragonflies). Both are available at their experience the need for a scientific collecting per- website, http://www.dragonflysoc.org.uk. mit in National Forests varies from state to state, de- spite the fact that they are all federally maintained. Some states require a fishing license if one is to col- Studying Odonata lect insects on these or other lands. City and municipal parks may also be protected, and you should Because many of the more common species can be contact the appropriate administering agency in seen almost anywhere, even far from water, it is easy these areas to inquire about collecting. Before issu- to begin studying odonates. And because they breed ing a scientific collecting permit, the administering in water, any relatively nonpolluted body of water agency will require a proposal of the research being will provide a good opportunity to observe them. conducted, and will mandate the depositing of Many are large enough to be observed and identi- vouchers (specimens accessioned or numbered) in a fied readily with a good pair of close-focusing binoc- legitimate and publicly accessible collection. ulars. But it is important to remember that not all In addition to the preservation and management species (particularly many damselflies) can be reli- of natural habitats, the creation of new habitats, es- ably identified without capture and closer examina- pecially ponds, can play an important role in con- tion. A small magnifying glass or jeweler’s loupe can servation. An artificial pond, especially one in an be useful for this kind of scrutiny in the field, and arid area, that has an assortment of aquatic vegeta- reversing a pair of binoculars will often work in a tion and a lush riparian zone protected from live- pinch. stock will provide productive breeding habitats for Remember that, in addition to observing the many species. Although many Odonata can coexist physical appearance of an odonate, you should note with fish in such ponds (as long as there is plenty of the habitat, season, and observed behavior. (How vegetation to hide in), the presence of fish will pre- and where does it perch? Does it spend most of its vent some species from persisting in the habitat. time perched or in flight?). Consideration of these We still have a lot to learn about the specific mi- characteristics jointly may yield a more confident crohabitat requirements of our individual Odonata identification. There are also certain physical fea- species. Although many species are at risk, others tures you will want to make careful notes or photo- (for example Great Spreadwing, Double-striped Bluet, graphs of as well. The color of the eyes and front of Widow Skimmer, and Swift Setwing), seem to be ex- the head, the pattern of thoracic stripes, the wing panding their ranges. It is unclear in most instances color or pattern, including the appearance of the if the expansion of these species is at the expense of pterostigma (colored cell at the tip of the wing), and others. We need more refined methods of popula- the color pattern of the abdomen are useful identi- tion estimation, ones that rely on exuvial and larval fying marks. counts rather than adult counts, if we are to begin It may become necessary to capture an odonate, getting at these questions. Collection and photogra- so as to examine it more closely in the hand. All you phy of individuals will also play a critical roll in fill- need if you are to capture one is an aerial net and a ing gaps in our knowledge and understanding of fair amount of hand-eye coordination. The best way species distributions. to handle an odonate is to pinch its wings together Both larvae and adults are recreationally impor- above its back, so that they stand straight up. They tant; fly fishermen have patterned tied flies after are generally unharmed by the experience and can them, and the terrestrial adults are observed and be released to carry on their activities after you have studied by layman and scientists because of their studied them. colors, flying ability, and curious habits. Odonates At some point you may choose to expand your have also served for centuries as favorite subjects of interests to the collection of odonates. Collecting poets, naturalists, artists, and collectors. Particularly small numbers of most odonates will have no harm- during this time of growing interest in the group, ful impact on their populations. Like other insects, we should be vigilant in our attempts to conserve they have a high reproductive potential. Most states aquatic habitats. The British Dragonfly Society has do not require a collecting permit, so long as you published two pamphlets dealing with dragonflies are not collecting in state, federal, or, in some cases,

For general queries, contact [email protected] © Copyright, Princeton University Press. No part of this book may be distributed, posted, or reproduced in any form by digital or mechanical means without prior written permission of the publisher. INTRODUCTION 9 municipal parks and preserves. Making a perma- your camera without having to get so close. Exten- nent a collection can be rewarding and will allow sion tubes can also be used with your macro lens to you to develop a greater appreciation for these in- increase magnification and or working distance. sects. Unfortunately, unlike some other insects, There is a trade-off, however: these longer lenses such as beetles and butterflies, odonates do not hold generally require the use of a tripod to prevent a their brilliant colors after death. The best way to blurred image. A tripod can be useful or even critical preserve these colors is to immerse the odonate in in the field, but it is also another piece of equipment acetone for 12–24 hours and then allow it to dry. that can brush up against vegetation, perhaps scar- This will fix the colors to some degree and will re- ing your subject away, and another thing to carry. move many of the fatty acids in the body that can There are many films on the market and I find discolor the specimen. Specimens for scientific that photographers are generally committed to a fa- study are generally placed in clear cellophane or vorite brand. Film speeds (ISO) are an indication of polypropylene envelopes with a 3 × 5 card record- the film’s sensitivity to light. The higher the ISO the ing the locality and other data pertinent to the col- more sensitive to light the film is, but also the lection of the specimen. grainier it is. I prefer Fuji films because of their satu- With the increase in popularity of odonates, re- rated colors, which produce a vivid image. I use 50 gional newsletters and societies are appearing, and or 100 ISO film, both of which work well on sunny in 1999 an active and informative international days. With the advent of high-resolution SLR digital email discussion group was created. The Interna- cameras, film may be less of an issue in the near fu- tional Odonata Research Institute (IORI) has a fairly ture. A few of the photographs in this book were complete assortment of field guides and books on taken with a digital SLR, which I now use exclusive- Odonata for sale. There are currently two interna- ly. The light sensitivity of the chip in the camera al- tional dragonfly societies (the Worldwide Dragonfly lows you to shoot at speeds as high as 400 and 800 Association and the International Odonatological ISO without the grain you would expect from film. Foundation, Societas Internationalis Odonatologi- I often employ a macro ring flash and one or two ca) that publish biannual and quarterly journals, re- slaved off-camera flashes. An electronic flash dedi- spectively. Another society, the Dragonfly Society of cated to your camera body with TTL (through-the- the Americas, produces a quarterly newsletter and lens) metering can be useful in close-up photo- an occasional journal. Anyone interested in Odo- graphy, both as direct lighting and fill-flash. Using nata in North America will find the small yearly flash as direct lighting will allow you greater depth dues for this society well worth the price. A full list of field and eliminate blurring from camera shake, of these societies with their contact information is because you can shoot at a higher shutter speed, but given at the back of the book in the Bibliography. some criticize the non-natural lighting that may result. It is also necessary to make sure that the background you are shooting against is not too distant, Photographing Odonata so that your resulting photo does not have a black background and appear as though it were taken at It probably won’t be long after you have started ob- night. serving odonates that you will want to begin photo- When photographing odonates, it is important graphing them. Given their beauty, this is a natural to make sure that your line of sight is completely extension of one’s interest. Most of the photographs perpendicular to the body surface you are photo- in this book were taken with a 35 mm SLR (single- graphing, so that the entire individual is in sharp fo- lens reflex) camera and a 100 or 180 mm macro cus. With large dragonflies, it is easy to have one lens. Damselflies, not as easily disturbed, are gener- end of the body—the head, say—in focus, but have ally easier to photograph, and if they do fly off, they the other end, the tip of the abdomen, a complete generally don’t fly far. Dragonflies, however, present blur. Many cameras come with a depth-of-field pre- a number of challenges. The longer the focal length view feature, which is helpful in placing the com- of the lens, the greater the working distance you plete insect in the focal plane. Another important will have. A 180–200 mm macro lens or a close- criterion is the background. You may not always be focusing 300 mm telephoto lens equipped with a able to choose this, but the better photographs have teleconverter will allow you to frame an odonate in contrasting backgrounds (blue sky, green vegeta-

My purpose here is to introduce briefly the termi- Thorax nology I use in this field guide when describing The thorax comprises three segments (pro-, meso- adult odonates. Table 1 summarizes some of the ma- and meta-), each bearing a pair of legs. The first jor differences between adult dragonflies and adult segment, the prothorax, is so reduced as to ap- damselflies; Figs. 4, 5, and 6 illustrate the particulars pear almost necklike, and articulates with the of odonate anatomy; and the Glossary furnishes fused mesothorax and metathorax. The wings definitions of most of the technical terms used in attach to the mesothorax and metathorax, which the figures and text. are much larger than the prothorax and sometimes jointly referred to as the pterothorax, because Head they are involved with wing function. Stripes are The large compound eyes are the most distinctive often visible on the pterothorax, and terms have feature on an odonate’s head. They make up the been applied to them (starting anteriorly, the mid- largest portion of the head, particularly in dragon- dorsal, antehumeral, humeral, anterior lateral, and flies. These eyes, composed of many small facets posterior lateral). (ommatidia) fused together, secure odonates as dominant aerial predators and some of the most ac- Wings robatic and skillful fliers in the animal world. As just mentioned, two pairs of wings attach to the The eye color is often one of the most distinctive last two thoracic segments. The wings are made up features of an odonate. In many the dorsal color of of numerous veins enclosing cells. The arrange- the eyes will differ from their ventral color, the dor- ment of the veins and cells is often useful in identi- sal surface usually darker. Unless stated otherwise, fying odonates. For that reason many of these, too, when eye color is given in the species accounts, I am have been accorded specific terms. One need not referring to the dorsal surface of the eye. Odonates become an expert on wing venation to identify see a wide spectrum of colors that includes not only most Odonata, but it is helpful to learn some of the the spectrum visible to us but also ultraviolet and general terminology used in this guide. I use the tra-

TABLE 1. DISTINGUISHING CHARACTERISTICS OF DAMSELFLIES AND DRAGONFLIES

Damselﬂies (Zygoptera) Dragonﬂies (Anisoptera)

Of slighter build, and generally weaker ﬂiers Of robust build, and strong ﬂiers

All wings similar in shape Hindwings broader basally than forewings

Wings held closed or nearly so over the abdomen Wings held horizontally outward from the body when at rest when at rest (except the spreadwings)

Eyes separated by at least their width Eyes touching or at least not separated by their width

Males with two pairs of caudal appendages Males with a pair of superior caudal appendages and a single inferior caudal appendage

Females with functional ovipositors True ovipositor lacking or reduced in females (except the darners and petaltails)

Pterostigma

Forewing

Nodus

Humeral stripe Hindwing Antehumeral stripe

Middorsal thoracic carina

A Abdomen

Frons Vertex Cercus

2nd lateral stripe 3rd lateral stripe Secondary genitalia

Epiproct

Occiput Eye seam

10 Cerci T Spot 1 2342 3 4 5 Antenna 6 7 8 9

Ovipositor B Pterostigma

Nodus

Thorax Compound eyes

Frons Femur

C Tibia Tarsus Ovipositor Fig. 4. Odonata adults, showing structures important in stigmatus), male; (B) Blue-eyed Darner (Aeshna multicolor), identiﬁcation: (A) Four-striped Leaftail (Phyllogomphoides female; (C) Elegant Spreadwing (Lestes inaequalis), female.

Anteclypeus Ocelli Postclypeus Labrum Vertex Occiput Antenna Mandible Posterior lobe Antenna Vertex Frons Compound eye Frons Postclypeus

Anteclypeus

Postocular spot Occiput Occipital bar B Labrum Lateral ocellus Median ocellus Mandible

A Humeral suture Middorsal stripe Median carina Metapleural suture Humeral stripe Mesostigmal plate

Prothorax AntehumeralMesepimeron stripe Metepisternum Metepimeron Femur

Spiracle Cerci

Coxa

Trochanter Tibia

Tarsi C Tarsal claw Paraprocts

Cercus

8 9 10

Paraproct D

Stylus Basal plate Ovipositor E

Fig. 5. Further structures important in odonate abdominal segments of female Swamp Spreadwing identiﬁcation: (A) head of damselﬂy, dorsal view; (B) head (Lestes vigilax), lateral view; (E) terminal abdominal of baskettail (Epitheca); (C) thorax of Variable Dancer (Ar- segments of male Great Spreadwing (Archilestes grandis), gia fumipennis), lateral view; (D) posterior ventral view.

Antenodal crossveins Costa Nodus Arculus Radius M 1 Rs

M3 AB Quadrangle M4 Cu1

Arculus Subtriangle Arculus Nodus

Subtriangle Triangle Paranal cell Membranule

Anal Triangle triangle Cu1 Cu Anal triangle 2 M4 Cu1 Anal loop CD Anal loop

Nodus Arculus Arculus

Triangle Triangle Cu 1 Cu1

Cu2

E F Anal loop Foot-shaped anal loop

Fig. 6. Wing details in Odonata: (A) forewing of janata); (D) basal hindwing of river cruiser (Macromia); broad-winged damsels (Calopterygidae); (B) basal (E) basal hindwing of baskettail (Epitheca); (F) basal hindwing of Orange-striped Threadtail (Protoneura cara); hindwing of skimmer (Libellulidae). (C) basal area of wings of Springtime Darner (Basiaeschna

For general queries, contact [email protected] © Copyright, Princeton University Press. No part of this book may be distributed, posted, or reproduced in any form by digital or mechanical means without prior written permission of the publisher. 14 INTRODUCTION ditional Comstock-Needham system of naming cated ventrally on segments 2 and 3. In damselflies, veins here, but there are several alternative systems the cerci are enlarged and form a dorsal pair of of nomenclature. A detailed comparison of these claspers. Below these is a pair of paraprocts. To- terms is given in Carle (1982). The strong anterior- gether with the cerci, these structures form the cau- most vein in each wing is called the costa. The cos- dal appendages, and are used for grasping the fe- ta is slightly notched toward the middle of its male during mating. In dragonflies, the paraprocts length at a region termed the nodus. The ptero- are reduced, and a single epiproct is located below stigma (sometimes called the stigma) is a colored the enlarged cerci. area at the tip of the wing along the costal margin. In dragonflies, there is a loop of veins near the base of Coloration the hindwing called the anal loop. These veins The beautiful and varied coloration of odonates is a present different shapes in different families. There significant factor in their appeal. In odonates, most are also areas of cells in the fore- and hindwings that of the colors seen result from pigment rather than make up triangles, supertriangles, and subtrian- from structural artifacts of the body. But the bright- gles. In dragonflies the configuration of these cells is blue color so characteristic of many damselflies is a useful in distinguishing among the different families. result not of pigment, but rather of the scattering of light by tiny refractive granules located in epider- Abdomen mal cells; and the metallic coloration seen in many The abdomen, elongated in all odonates, comprises emerald dragonflies is also a result of the insects’ ten segments, the first and last of which are re- surface structure. In many odonates a pruinescence, duced and often hard to see. The color pattern on or waxy blue-white covering, will develop with age, these segments is often useful in making field iden- and as noted above, the newly emerged, or teneral, tifications, especially with many of the damselflies. adult will not have the vibrant colors of its mature (In some cases, especially the clubtail dragonflies, counterpart. the terminal segments will be dilated into a clublike In many cases, coloration is an important and structure.) Females typically have slightly broader useful tool for making field identification, but it is abdomens than males, and in damselflies, darners, important to recognize some of the difficulties of and petaltails an ovipositor (a bladelike egg-laying using color. Odonates of many species are sexually structure) is evident ventrally on the female’s seg- dimorphic in this respect; the males and females ment 9. Those dragonflies lacking an obvious ovi- differ in coloration. Moreover, many species of positor have a subgenital plate (vulvar lamina) damselflies and darners are known to change colors originating ventrally from segment 8 and extending with temperature; individuals will often become to segment 9. It is often notched at its middle. A darker in color when exposed to cooler tempera- pair of cerci (sing. cercus), extending terminally, is tures. This is important to remember when observ- usually visible, though in most groups these are re- ing odonates on a cool early morning. Several spe- duced in the female. cies of pond damsels, such as Springwater Dancer, Males have secondary, or accessory, genitalia, lo- also become darker while in copulation.

A GUIDE TO THE SPECIES ACCOUNTS

The species accounts in genera. Two of the ten families, the pond damsels this book treat 85 spe- (Coenagrionidae, 66 spp.) and the skimmers (Libel- cies of damselﬂies and lulidae, 81 spp.), account for 56% of our total 178 species of dragonﬂies, all occurring in the species and six of our 69 genera (Lestes, 10 spp.; Is- south-central United States. These 263 Odonata chnura, 12 spp.; Gomphus, 12 spp.; Libellula, 17 spp.; species are distributed among ten families and 69 Argia, 22 spp.; and Enallagma, 23 spp.) number ten

KEY TO THE FAMILIES OF SOUTH-CENTRAL ODONATA

1. Fore- and hindwings similar in size and shape, Damselﬂies (Suborder Zygoptera, p. 19) 2 having quadrangles instead of triangles and sub- triangles; eyes well separated on top of the head, by more than their own width

1. Fore- and hindwings not similar in size and Dragonﬂies (Suborder Anisoptera, shape, the hindwing considerably wider basally, p. 149) 5 each wing having a triangle and a subtriangle; eyes meeting middorsally on top of the head, or, if separated, then by less than their width

2(1). Numerous antenodal crossveins; postnodal Broad-winged Damsels (Family crossveins not in line with veins posterior to Calopterygidae, p. 21) them

2. Only 2 antenodal crossveins; postnodal cross- 3 veins in line with veins posterior to them 3(2 ). Veins M3 and Rs arise nearer to the arculus Spreadwings (Family Lestidae, p. 29) than to the nodus 3 . Veins M3 and Rs (see Fig. 6) arise nearer to the 4 nodus than to the arculus 4(3 ). Anal vein absent or greatly reduced; Cu2 ab- Threadtails (Family Protoneuridae, p. 46) sent or at most only 1 cell long 4 . Anal vein and Cu2 not absent or reduced Pond Damsels (Family Coenagrionidae, p. 52)

5(1). Eyes widely separated on top of the head 6

5. Eyes touching or only narrowly separated on top 7 of the head

6(5). Pterostigma at least 1/4 the distance from Petaltails (Family Petaluridae, p. 151) nodus to wing apex; body color gray and black; front margin of labium with a median cleft

KEY TO THE FAMILIES OF SOUTH-CENTRAL ODONATA (cont.)

6. Pterostigma not more than 1/6 the distance from Clubtails (Family Gomphidae, p. 176) nodus to wing apex; body color yellow or green with black (if gray, then total length less than 70 mm); front margin of labium without a median cleft

7(5). Eyes narrowly touching or barely separated on Spiketails (Family Cordulegastridae, p. 215) top of the head

7. Eyes broadly touching on top of the head 8

8(7). Triangles in fore- and hindwings similar in Darners (Family Aeshnidae, p. 153) shape 9 8. Triangles in fore- and hindwings dissimilar

9(8). Anal loop generally foot-shaped, with well- Skimmers (Family Libellulidae, p. 240) developed toe; no tubercle on rear margin of each compound eye

9. Anal loop either foot-shaped, but with little de- Emeralds & Cruisers (Family Corduliidae, velopment of the toe, or circular and not foot- p. 218) shaped; generally a tubercle on rear margin of each compound eye

or more species each and collectively account for is known throughout the world, (3) identifiying 38% of the total species. numbers for figures, photos, and tables illustrating Family and generic accounts introduce the re- or characterizing the species, (4) measurements, in- spective groups and include keys to genera and spe- cluding total length, length of the abdomen, and cies. Keep in mind that in many cases information length of the hindwing, (5) lists of the regional biot- given in these sections is restricted to what is ap- ic provinces and watersheds where the species is plicable to the odonates of the south-central United known to occur (see Figs. 1 and 2, in the Introduc- States fauna. Species accounts include illustrations tion), (6) the species’ general distribution, (7) flight and photographs that will allow you to identify season within the region (state abbreviations are giv- odonates in the region. I have intentionally en in parentheses; early and late dates are reported cropped many of the photographs in an attempt to from the literature and museum collections; in some better show specific characters. This is especially cases, where specimens and data are scarce, only one true in the dragonflies, where in some areas I have date may be known for our region), (8) a description cropped out one set of wings (especially when they of the species, emphasizing tips on identification, (9) were clear), to reveal more detail on the thorax and notes on similar species encountered in our region, abdomen. Families are organized phylogenetically with details on their differences, (10) a brief descrip- (along lines of their relationships), but for ease in tion of the species’ preferred habitats, (11) a discus- accessing family members, the genera and species sion of behavior and other matters, and (12) a selec- are arranged alphabetically by scientific name. tion of the relevant literature pertaining to the Individual species accounts consist of the follow- species (all sources cited in text are given in the Bib- ing information: (1) common (English) name, taken liography). Accompanying each species account is a from Paulson and Dunkle (1996) and updated when map of the species’ distribution within our region necessary at http://www.ups.edu/biology/museum/ (updated through June 2002). NAdragons.html, (2) scientific name, as the species Figs. 7 through 32, falling at various points

For general queries, contact [email protected]