Information

Identify these two large, colorful dragonflies in Taiwan?

Identify these two large, colorful dragonflies in Taiwan?


We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

Here are two dragonflies that I photographed today in Hsinchu county Taiwan. They are both quite large, with a body length of about 5 or 6 cm.

I often see them in the same pond or nearby marshy area. They seem pretty confident and are easy to photograph as long as you don't make a big commotion.

The arrows were drawn for my other question Why do dragonflies have these special little spots on their wings?

Is it possible to identify these two species? I can break them out as separate questions if necessary; I don't want to flood the site with "identify this dragonfly" questions.

The first is jet-black everywhere except for a robins-egg blue powdery coloration along the top side of the first two-thirds of it's abdomen. It's wings, like most but not all dragonflies, are transparent.

The second has some amount of red almost everywhere; its eyes and thorax are dull red and it has bright red patches on each segment of its abdomen. Notably its wings are solid opaque red, except for the furthers 1 cm which is transparent. The tiny "special spots" on the tips of each wing are a particularly bright shade of red!


Looks like this species is Orthetrum triangulare commonly known as blue-tailed forest hawk. It is an Asian fresh water dragon fly species.

As you mentioned that the dragonfly had a bluish hue, it became clear.

The other one looks like Neurothemis ramburri, commonly known as red perch Reference

Neurothemis is a genus of dragonflies in the family Libellulidae. Most Neurothemis species are red in color. Neurothemis ramburii (Brauer, 1866) is distributed from Sundaland to New Guinea. There are records from Peninsular Malaysia, Taiwan, the Andaman Islands, Sumatra, Java, Borneo (Sarawak, Sabah, Brunei and Kalimantan), the lesser Sunda islands, the Philippines, the Bismarck islands and New Guinea. It is a widely distributed and common species that thrives in disturbed habitats.


Dragonflies: Facts, Symbolic Meaning, and Habitat

The dragonfly and its smaller cousin, the damselfly, belong to an ancient order of insects known as Odonata and have carried symbolic meaning for centuries. Most people love to have dragonflies in their gardens, if only because dragonflies love to eat mosquitoes.

Who hasn’t marveled at the aerial abilities of dragonflies as they glide effortlessly over sparkling streams, pristine ponds, and lakes, plucking insects from the air with deadly precision?

Dragonfly Facts and Life Cycle

Surprisingly, these brilliantly colored masters of the air are classified as aquatic insects because they spend most of their lives as larvae underwater among plants or in silt. They may spend five years or more in the larval stage, molting several times before emerging as adults—and then living only a few weeks to a few months.

With keen eyesight and expert airmanship, dragonflies and damselflies easily outmaneuver and catch insect prey. Their four gossamer wings move independently of one another, giving them the ability to fly forward, backward, and sideways, or to just hover in place. Bead-like eyes provide 360–degree stereovision, allowing them the ability to spot insects in any direction without turning or moving their heads. (In fact, dragonflies have the biggest eyes in the insect world.)

Dragonflies and damselflies, though similar in their life cycle and appearance, fly differently. You can distinguish them by noticing that dragonflies fly directly and with purpose, while the damselfy’s flight is more fluttery. The damselfly also has a slightly longer abdomen.

A damselfly has the same captivating appearance as a dragonfly, but it is a bit smaller and its eyes are farther apart.

What do dragonflies eat? The dragonflies’ and damselflies’ fondness for mosquitoes puts them in the category of beneficial insects, but they eat many other annoying bugs. Their diet includes midges, moths, flies, and other flying insects. Unfortunately, they also sometimes eat butterflies. This means that planting flowers that attract butterflies might keep your yard full of both species.

Dragonflies aren’t just beneficial as mosquito-eaters. Their role as barometers of wetland health is also very important. In order to survive, odonate larvae need clean, well-oxygenated water. Drainage of wetlands, pollution from farming and industry, and the development of new roads and houses have increasingly reduced dragonfly habitat. Conservation of existing wetlands is key to odonate survival, as is providing new habitats for them to colonize.

Fossil records show that dragonflies were around for 100 million years before the dinosaurs. These prehistoric predators had wingspans of over three feet and are the largest insects known. Imagine if they were that big now—a dainty dragonfly landing on your finger would not seem quite so charming!

Dragonfly Meaning and Symbolism

  • Many Americans believe that it is good luck if a dragonfly lands on you without prompting. Dragonflies are also a symbol of good luck in Chinese tradition.
  • Dragonflies have been a notable part of folklore in many countries, especially Japan. Japanese tradition views dragonflies as symbols of swiftness and as a sign of summer and autumn.
  • Dragonflies have been a symbol of purity, activity, and swiftness for some Native Americans. The indication of purity comes from both the pure water in healthy aquatic habitats where dragonflies thrive and from the fact that they eat their food right out of the wind.
  • Some common names for dragonflies are “Mosquito Hawk,” “Devil’s Darning Needle,” and “Snake Doctor.” Mosquito Hawk stems from the dragonfly’s favorite food, Devil’s Needle stems from very old traditions indicating that dragonflies were evil, and Snake Doctor stems from the fact that dragonflies can often be seen in the same habitat as snakes and sometimes even interact with them.

How to Attract Dragonflies to Your Garden

  • Constructing a pond or other backyard water feature will attract a surprising number of dragonflies and damselflies. Size is not crucial, but dig the basin deep enough so that the water won’t freeze solid in the winter. Plant a few native plants at its edge for wind protection. The pond should get at least partial sun.

Dragonflies are born and spend most of their lives in aquatic habitats, so you can attract them by building a pond in your yard.

  • If you already have a pond in your yard or are considering building one, it helps to have some vertical plants coming out of the water. This is where the female dragonflies and damselflies will lay their eggs.
  • By providing needed habitat, you can help save dragonflies as well as damsels in distress.
  • Be aware of the pesticides you are using to get rid of annoying bugs like mosquitoes—they also might be harming beneficial insects like dragonflies. Look at our tips for how to deter mosquitoes instead. Remember that if you’re not controlling the mosquito population, hopefully the dragonflies will!

You can read more about the marvels of dragonflies in this blog about appreciating the beauty of the insects with rainbows for wings.


Here Be Dragons: Sixty New Species of Dragonflies Discovered in Africa

Seven hundred species of dragonflies and damselflies were known to inhabit continental Africa. But recently, researchers published descriptions of 60 new species in the specialist journal Odonatologica, which dramatically increases the number of named African species. Discovered by an international team of dragonfly experts ("odonatologists"), naturalists and school teachers during a period of fifteen years, this is the greatest number of new dragonfly and damselfly species to be formally described at the same time in 130 years.

Chasing after that "living flash of light"

As insects go, odonates -- dragonflies and damselflies -- are well-known. Worldwide, more than 6,000 species have been named. Yet, this one paper, the result of 15 years' work, has added 60 more species, increasing the total number known for Africa alone to 760 species.

“The current emphasis on molecular research in taxonomy creates the impression that undiscovered life is inconspicuous or hidden,” said lead author and dragonfly expert, Klaas-Douwe Dijkstra, a member of the International Union for Conservation of Nature (IUCN) Species Survival Commission Dragonfly Specialist Group and an honorary research associate at the Naturalis Biodiversity Center in the Netherlands.

Klaas-Douwe B. Dijkstra identifies newly-collected odonates in the field. (Credit: Kris . [+] Pannecoucke/Royal Museum for Central Africa.)

“[B]ut each of our new species is colorful and easy to identify”, Dr Dijkstra pointed out in email.

Remarkably, despite their conspicuousness, only nine of the 60 new species were discovered by a professional biologist whilst he worked for a university or museum on academic time 21 more were discovered by the biologist working as a paid consultant, and the rest by a teacher or professional consultant -- in their spare time.

“Anyone who deepens their interest in nature and goes out to look, can find new species”, said Dr Dijkstra. “It’s a matter of going outside and knowing what you’re looking for.”

Dragonfly hunting on the Congo River in Africa. (Credit: Kris Pannecoucke/Royal Museum for Central . [+] Africa.)

Unnamed species are invisible species

“Introducing species to society and into our [consciousness] has general importance”, said Dr Dijkstra. “Nature needs names. Like a person’s name, they allow us to care.”

“As one budding enthusiast exclaimed to me: 'You don’t notice them until you know they have a name!'” added Dr Dijkstra.

Names chosen by taxonomists consist of a common name and a binomial, or scientific, name, which is either Latin or is "Latinised". Whilst the common name may change to reflect local or popular usage, and may be shared with other species, the scientific name, which conforms to specific nomenclatural rules, is unique and stable only changing to reflect new developments in our understanding of species relationships.

Since the assigned binomial is more or less permanent, naming a new species can be challenging and perhaps somewhat intimidating, but it provides an opportunity for researchers to add some poetry to science. Thus, a number of strategies are used to name newly identified species. For example, some names are descriptive.

“Males of the Polychrome Jewel, Africocypha varicolor, from Gabon, for example, are not just black, blue, green and red, but can also have a red, blue or yellow tail-end", said Dr Dijkstra.

The newly-described polychrome jewel (Africocypha varicolor), blue form, from Gabon in Africa. . [+] (Credit: Andre Guenther/Klaas-Douwe B. Dijkstra, Jens Kipping & Nicolas Mézière, doi:10.5281/zenodo.35388/Odonatologica 2015.)

“We have no idea why”, added Dr Dijkstra. “Maybe females have different preferences? Or males are signalling something about their own or their territory's condition?”

The newly-described polychrome jewel (Africocypha varicolor), yellow form, from Gabon in Africa. . [+] (Credit: Andre Guenther/Klaas-Douwe B. Dijkstra, Jens Kipping & Nicolas Mézière, doi:10.5281/zenodo.35388/Odonatologica 2015.)

Other names refer to local words or events. For example, the peace sprite, Pseudagrion pacale, was discovered on the Moa River near Sierra Leone’s diamond capital, Kenema. Twenty years earlier, fleeing villagers became trapped between rebel and government forces on opposite banks of this river, and drowned. Perhaps ironically, Kenema became the epicentre of an Ebola outbreak just two years later.

The team named some species after people who helped or inspired them. For example, the dawn jewel, Chlorocypha aurora, was named to honour Dr Dijkstra’s colleagues at DAWN (the Damselfly Workers at Naturalis).

The newly-described dawn jewel (Chlorocypha aurora), from Cameroon in Africa. (Credit: Jens . [+] Kipping/Klaas-Douwe B. Dijkstra, Jens Kipping & Nicolas Mézière, doi:10.5281/zenodo.35388/Odonatologica 2015.)

Although naming a species after yourself is forbidden, the other team members named the newly discovered blue-spotted pricklyleg, Porpax mezierei, in honour of co-author Nicolas Mézière, who worked as a secondary school teacher in Gabon for seven years whilst chasing dragonflies and damselflies in his spare time. Mr Mézière discovered 18 of these 60 newly identified species.

“Nico [Nicolas Mézière] is the author of the paper this species is described in, but not of the description itself, and so we've avoided any immodesty from his side!” said Dr Dijkstra.

Of course, some names are light-hearted and intended to attract the public's attention. The best example of this is the robust sparklewing, Umma gumma, which is named for the 1969 classic Pink Floyd album “Ummagumma”, slang for making love.

Newly identified African damselfly, the robust sparklewing (Umma gumma). (Credit: Jens . [+] Kipping/Klaas-Douwe B. Dijkstra, Jens Kipping & Nicolas Mézière, doi:10.5281/zenodo.35388/Odonatologica 2015.)

Dragonflies and damselflies indicate the quality of freshwater habitats

Odonates are exclusively dependent upon freshwater habitats. They lay their eggs in freshwater, their larvae are aquatic, and the adults maintain freshwater territories for reproduction. Thus, they are sensitive to structural changes in their homes, such as erosion and loss of vegetation cover, and changes in water clarity and water flow, just to name a few things. By monitoring the diversity of odonate species and their relative numbers present on a body of water, observers can obtain fine-grained data about the types of structural changes taking place in a particular watershed. Long-term monitoring of odonate communities is an accessible and important way for human communities to assess ongoing changes within a particular ecosystem.

Although less than 1% of the Earth's surface is covered with freshwater, these habitats are home to 10% of all animal species (doi:10.1146/annurev-ento-011613-161958). Due to intense human exploitation by mining, damming, fishing, land-clearing and agriculture, freshwater-dependent species are more likely to be endangered than those living anywhere else. These pressures will only increase: the global human population, which surpassed 7 billion people sometime in 2012, is projected to grow to 11 billion people by 2100, and 83% of that growth is predicted to occur in African nations.

Klaas-Douwe B. Dijkstra demonstrates how to collect dragonflies and damselflies in the field. . [+] (Credit: Kris Pannecoucke/Royal Museum for Central Africa.)

At the same time that museum collections are becoming increasingly digitised, our knowledge of the various life forms present in areas that are most vulnerable to increasing human populations is unfortunately incomplete, as this 233-page paper indicates. For this reason, unidentified species can be wiped out of existence before we ever know they are present -- and certainly before we learn anything about them.

At the same time that museum collections are becoming increasingly digitised, natural history museums and taxonomists receive fewer and fewer funds to conduct research to identify, describe and name species, to go into the field to learn more about these species, and to share their knowledge with the public in a meaningful way.

“Biodiversity science seems to be hurtling towards a state where all available data may be accessible, but where fewer and fewer people know what these data mean”, observed Dr Dijkstra.

“For example, none of the world's great Odonata collections has a dedicated researcher anymore”, added Dr Dijkstra. “Just serving the tens of thousands worldwide who simply enjoy these insects' beauty, would make it worth it.”

Making this information freely available online is a step in the right direction because it serves to increase public awareness of these animals, of their intrinsic value, and of their value to humans. And of course, such discoveries may serve to inspire a new generation of odonatologists, whether they are amateurs or professionals, and whether they seek these insects with a camera, a microscope or a DNA sequencer.

“We see this effort as a call to science and the public: make the search for unknown life a priority before it’s too late,” said Dr Dijkstra.

“In freshwater alone a quarter million species could be gone before they are known. Nature needs more explorers now!”

“Nature needs more explorers now!” (Credit: Alan Manson/Klaas-Douwe B. Dijkstra, Jens Kipping & . [+] Nicolas Mézière, doi:10.5281/zenodo.35388.)

Klaas-Douwe B. Dijkstra, Jens Kipping & Nicolas Mézière (2015). Sixty new dragonfly and damselfly species from Africa (Odonata), Odonatologica 44(4): 447-678 | doi:10.5281/zenodo.35388

Klaas-Douwe B. Dijkstra, Michael T. Monaghan, and Steffen U. Pauls (2014). Freshwater Biodiversity and Aquatic Insect Diversification, Annual Review of Entomology 59:143-163 | doi:10.1146/annurev-ento-011613-161958

Although I look like a parrot in my profile picture, I'm an evolutionary ecologist and ornithologist as well as a science writer and journalist.

As a writer, my passion is

Although I look like a parrot in my profile picture, I'm an evolutionary ecologist and ornithologist as well as a science writer and journalist.


Introduction to the Odonata

Both dragonflies and damselflies belong to the Odonata, which is a subgroup of insects, which in turn is a group of uniramian arthropods. Many characteristics distinguish Odonata from other groups of insects -- minute antennae, extremely large eyes (filling most of the head), two pairs of transparent membranous wings with many small veins, a long slender abdomen, an aquatic larval stage (nymph) with posterior tracheal gills, and a prehensile labium (extendible jaws underneath the head). Among living Odonata, there are twenty-five families, mostly dragonflies and damselflies. Of all their characteristics, the easiest way to tell a dragonfly or damselfly from other insects is by the size of the eyes and shape of the abdomen. If the eyes are very large in proportion to the head and the abdomen is long and thin, then it is almost sure to be in Odonata.

While both dragonflies and damselflies belong to the Odonata and share many common features, then are a number of noticeable differences as well. Even before hatching from the egg, differences in morphology of the egg distinguish dragonflies (Anisoptera) from damselflies (Zygoptera). Dragonfly eggs are round and about 0.5 mm long, whereas damselfly eggs are cylindrical and longer, about 1 mm long. Similarly, the nymphs (larvae) of the two groups differ. A larval damselfly abdomen is longer and narrower with three fin-like gills projecting from the end. Dragonfly nymphs are shorter and bulkier, and the gills are located inside the abdomen. The dragonfly nymph expands and contracts its abdomen to move water over its gills, and can squeeze the water out rapidly for a short burst of underwater jet propulsion.

Most of a dragonfly's life is spent in the larval stage where it molts from six to fifteen times. Depending on altitude and latitude, larval development varies from the common one or two years to as many as six years. At that time, the nymph crawls up out of the water and molts one last time, emerging from its old skin as an adult with functional wings. Unlike butterflies and beetles, dragonflies and damselflies do not have an intermediate pupal stage before becoming an adult. Because of this, Odonata are said to be hemimetabolous, or undergo an "incomplete" or "gradual" metamorphosis.

Both major suborders have large heads with very large compound eyes relative to the rest of their body. Each compound eye is composed of nearly 28,000 individual units (ommatidia), and together the eyes cover most of the head. More than 80% of their brain is devoted to analyzing visual information. By contrast, their antennae are tiny. Their mouths have been adapted for biting, making them efficient hunters. All Odonata have a prehensile labium, which can be extended forward from underneath the head faster than most prey can react, making their bite fatal to prey. The six legs are all located near the head and are seldom used for walking, but are more useful in catching prey and perching on vegetation to rest or lay eggs.

Both dragonflies and damselflies have two pairs of elongated membranous wings with a strong crossvein and many small veins that criss-cross in the wings, adding strength and flexibility to the wings. Both groups also have a characteristic nodus, or notch, in the front edge of each wing. In dragonflies, the rear wings have a broader base and are larger than the front pair. Damselflies, by contrast, have front and hind wings similar in shape, and as a result they fly slower than dragonflies do. Also, dragonflies do not have hinges enabling them to fold their wings together when resting, though damselflies do. This feature of the wings is the key morphological feature distinguishing adult dragonflies from damselflies.

Dragonflies can fly forward at about 100 body-lengths per second, and backwards at about 3 body-lengths per second. They are also capable of hovering in the air for about a minute. Longer periods of stagnant flight would interfere with thermoregulation. The wings of male dragoinflies are relatively longer and narrower than females in large species. Adult wingspans measure from 17 millimeters (Agriocnemis) to 20 centimeters (Coerulatus). Most temperate zone species have wingspans of 5 to 8 centimeters and wings that are from two to twelve centimeters from front to back.

The Odonata are known to be ancient insects. The oldest recognizable fossils of the group belong to the Protodonata, an ancestral group that is now extinct. The earliest fossils so far discovered come from Upper Carboniferous (Pennsylvanian) sediments in Europe formed about 325 million years ago. Like modern-day dragonflies, the Protodonata were fast-flying with spiny legs that may have assisted in capturing prey their wingspan was up to 75 centimeters (30 inches). The group went extinct in the Triassic, about the time that dinosaurs began to appear.

Fossilized specimens of another group, the Protoanisoptera (family Meganeuridae), have been found in limestone at Elmo near Abilene, Kansas, USA. The Meganeuridae differed from modern Odonata in a number of ways -- they lacked a nodus (wing notch) and pterostigma (features of the wings) and were enormous compared to modern species. Fossils of these insects with seventy centimeter wingspans have been found in Commentry, France, and a fifty centimeter specimen was found in Bolsover in Derby, both in Carboniferous layers.

Though the Carboniferous specimens are the oldest fossils of this group found to date, they were not the first specimens to be discovered. The first Odonata fossils were found in sediments from the Lower Permian, over 250 million years old. These fossils are not huge monsters like the Carboniferous fossils, but belong to relatively small Protoanisopterans and Zygopterans (damselflies). The latter seem to have changed little in structure and appearance since then. However, it is currently a question of debate as to whether members of Protodonata and the earliest Odonata had aquatic larvae, as do all modern species, since no Paleozoic larvae fossils are known. Larvae do not exist as fossils before the Mesozoic. Some workers believe that Odonata adopted an aquatic larval stage during the Lower Permian, perhaps because their prey lived in aquatic habitats. In any event, several groups of Odonata existed by the Late Paleozoic, though only three members of this group survive today.

Dragonflies are generalists, that is, they eat whatever suitable prey is abundant. Oftentimes, they hunt in groups where large numbers of termites or ants are flying, or near swarms of mayflies, caddisflies, or gnats. According to most studies, the main diet of adult odonates consists of small insects, especially Diptera (flies). Maturing dragonfly larvae feed very intensively, as do females when developing their eggs. Studies show that food shortage may limit reproductive behavior. Dragonflies do not hunt in cold weather. Damselflies, however, are not as limited by temperature and have been observed hunting during cold spells. Males are territorial, sometimes patrolling for prey for hours at a time.

Though dragonflies are predators, they themselves must be wary of many predators. Birds, lizards, frogs, spiders, fish, water bugs, and even other large dragonflies have all been seen eating odonates. However, dragonflies have many adaptations enabling them to avoid predation. They have exceptional visual responses and truly agile flight.

Although many insects perform courtship, it is uncommon among dragonflies. Anisoptera copulate while in flight, the male lifting the female in the air. Zygoptera copulate while perched, sometimes flying to a new perch. The length of time required for copulation varies greatly. Aerial copulations may last mere seconds to one or two minutes. Perched copulations usually last from five to ten minutes. Intraspecific competition amongst males for females is fierce. It has even been discovered that in some species of Odonata, the males will remove all the sperm of rival males from a female's body before transferring his own sperm. These species are equipped with a "scoop" at the tip of the male's abdomen that is used for this purpose.

The distribution of various groups and species of Odonata is highly variable. Some genera and species are widespread while others are highly local in their distribution. Some families are restricted to cool streams or rivers, others to ponds or still clear waters, and some to marshy places. The presence of dragonflies and damselflies may be taken as an indication of good ecosystem quality. The greatest numbers of species are found at sites that offer a wide variety of microhabitats, though dragonflies tend to be much more sensitive to pollution than are damselflies. Many ecological factors affect the distribution of larvae. The acidity of the water, the amount and type of aquatic vegetation, the temperature, and whether the water is stationary or flowing all affect the distribution of Odonata larvae. Some species can tolerate a broad range of conditions while others are very sensitive to their environment.

    The International Odonata Research Institute is devoted to the study of dragonflies and damselflies and is part of the Odonata Information Network.


Female

Body: Often thicker in the abdomen.

Ovipositor: Appendage used for egg laying. Located under segment 8-9 of the abdomen.

Female Southern Hawker dorsal image by Ian Worsley

Female Southern Hawker side image by Ian Preston

In many species of dragonflies adults change colour as they mature.

Tenerals: Newly emerged adults are often paler in colouration.

Mature adults: As an adult becomes sexually mature this is often indicated by a change in coloration.

Over mature: In some species, adults become darker in coloration as they age.

Mature Female Common Darter image by Andrew Holloway

Over-mature Female Common Darter image by Charlie Jackson

Immature Male Common Darter by Iain Leach

Dragonflies and Damselflies of the West

Dragonflies and Damselflies of the West is the first fully illustrated field guide to all 348 species of dragonflies and damselflies in western North America. Dragonflies and damselflies are large, stunningly beautiful insects, as readily observable as birds and butterflies. This unique guide makes identifying them easy&thinsp—&thinspits compact size and user-friendly design make it the only guide you need in the field. Every species is generously illustrated with full-color photographs and a distribution map, and structural features are illustrated where they aid in-hand identification. Detailed species accounts include information on size, distribution, flight season, similar species, habitat, and natural history. Dennis Paulson’s introduction provides an essential primer on the biology, natural history, and conservation of these important and fascinating insects, along with helpful tips on how to observe and photograph them.

Dragonflies and Damselflies of the West is the field guide naturalists, conservationists, and dragonfly enthusiasts have been waiting for.


  • Covers all 348 western species in detail
  • Features a wealth of color photographs
  • Provides a color distribution map for every species
  • Includes helpful identification tips
  • Serves as an essential introduction to dragonflies and their natural history

Awards and Recognition

"Who knew that there were 348 species of dragonflies and damselflies in the Western United States? That fact alone should make nature lovers who enjoy traveling to wild places want to check out Dennis Paulson's new book, Dragonflies and Damselflies of the West, published by Princeton University Press. . . . This guide includes information on flight seasons, habitat and natural history in the description of each insect as well as helpful tips on how to observe and photograph them."Salt Lake Tribune

"Bird watching has been a common hobby for centuries, and butterfly watching has become popular in the last few decades. Odonate watching is the newest pastime. Here, Paulson offers a comprehensive guide to Odonata of western North America. . . . This well-written, informative guide is a 'must have' for any person, amateur or scholar, interested in these insects."Choice

"[T]hese volumes are obviously authoritative, comprehensive and clearly designed with the needs of the naturalist in mind. The photographs are excellent and . . . the text makes up for the unavoidable shortcomings of a photo-guide by including full descriptions of each species. Altogether, these two volumes constitute a complete, highly informative and beautifully illustrated guide to the Odonata of North America."—Guy Padfield, UKbutterflies

"Extremely well organized, and very well written. This is a superb treatment. With its impressive number of large, clear images and thorough text, it will immediately become the must-have field guide for western odonate watchers and researchers."—Giff Beaton, author of Dragonflies and Damselflies of Georgia and the Southeast

"Dennis Paulson is recognized as one of the very best odonatologists in the world. This is a fine book, and will sell many thousands of copies. The text is well organized, and the color photos are gorgeous."—Sidney W. Dunkle, author of Dragonflies through Binoculars

Related Books


Materials and methods

Species sampled and microscopy

Adult (post-teneral) specimens of Enallagma civile (Hagen)(Coenagrionidae) and male Anax junius (Drury) (Aeshnidae) were collected in Lawrence, KS, USA in August 2002 and June 2003 by R.O.P. Specimens of Enallagma and Anax were fixed in Karnovsky's fixative (2.5% glutaraldehyde, 2.5% paraformaldehyde) for 12 h, stored in cacodylate buffer and prepared for TEM by a standard protocol(Prum and Torres, 2003b). These specimens were sufficiently preserved to reveal the general anatomy of the cuticle and epidermal pigment cells, but they showed extensive degradation of the colour-producing nanospheres within the pigment cells. To improve preservation of the nanostructure of the light-scattering spheres, a subsequent sample of four Enallagma civile were fixed and embedded following the rapid method of Hayat and Giaquinta(1970). Specimens were sectioned (∼100 nm thick) with a diamond knife and viewed with a JEOL EXII transmission electron microscope. Digital micrographs were taken with a Soft-Imaging Megaview II CCD camera (1024×1200 pixels).

Reflectance spectra

Reflectance spectra of living Enallagma and Anax were measured with an Ocean Optics USB2000 fibre optic spectrophotometer and Dell laptop computer. Reflectance was measured with normal incident light at 6 mm distance from a 3 mm 2 patch of the integument. The colour of preserved specimens changed rapidly to a deep brown or black with no measurable hue.

2-D Fourier analysis

Coherent scattering of visible wavelengths is a consequence of nanoscale spatial periodicity in refractive index of a tissue. Following a theory of corneal transparency by Benedek(1971), we have developed a method of using the discrete 2-D Fourier transform to analyze the periodicity and optical properties of structural coloured tissue and to predict its reflectance spectrum due to coherent scattering (Prum et al., 1998, 1999a,b, 2003 Prum and Torres, 2003a,b).

The digital TEM micrographs of the rapidly fixed specimens of Enallagma civile were analyzed using the matrix algebra program MATLAB (version 6.2 www.mathworks.com)on a Macintosh G4 computer. The scale of each image (nm pixel –1 ) was calculated from the number of pixels in the scale bar of the micrograph. A 1024 pixels 2 portion of each array was selected from each image for analysis. Because the molecular composition of the colour-producing nanospheres is unknown, we could not calculate an average refractive index of the nanostructure based on the frequency distribution of its components as in our previous applications of the method. However, we estimate the average refractive index of the material within the spheres necessary to produce congruence with the observed reflectance spectrum.

The Fourier transform was calculated with the 2-D fast Fourier transform(FFT2) algorithm (Briggs and Henson,1995). We then calculated the 2-D Fourier power spectrum, or the distribution of the squares of the Fourier coefficients. The 2-D Fourier power spectrum resolves the spatial variation in refractive index in the tissue into its periodic components in any direction from a given point. The 2-D Fourier power spectrum was expressed in spatial frequency (nm –1 ) by dividing the initial spatial frequency values by the length of the matrix(pixels in the matrix × nm pixel –1 ).

We calculated radial averages of the power spectra using 100 spatial frequency bins, or annuli, between 0 and 0.02 nm –1 and expressed them in terms of % total Fourier power. Composite radial averages were calculated from a sample of power spectra from five TEM images of the best preserved Enallagma sections to provide an indication of the predominant spatial frequency of variation in refractive index in the tissue over all directions.

We produced predicted reflectance spectra for Enallagma civilebased on the 2-D Fourier power spectra of the TEM micrographs, the image scales, estimated values of the average refractive index of the material and estimating the expansion of the arrays during preservation. First, a radial average of the % power was calculated for concentric radial bins, or annuli,of the power spectrum corresponding to fifty 10 nm-wide wavelength intervals between 300 and 800 nm (covering the light spectrum visible to insects). The radial average power values were expressed in % visible Fourier power by normalizing the total power values across all potentially visible spatial frequencies (i.e. potentially scattering light between 300 and 800 nm) to 1. The inverse of the spatial frequency averages for each wavelength were then multiplied by twice the estimated average refractive index of the medium and expressed in terms of wavelength (nm). A composite predicted reflectance spectrum was produced by averaging the normalized predicted spectra from a sample of five TEM images of Enallagma civile. Values of the average refractive index and % expansion during tissue preparation were estimated by producing a reflectance spectrum congruent with the observed reflectance peaks.

Phylogenetic analysis

The distribution of non-iridescent blue integumentary structural colour was estimated from a review of odonate diversity (by J.A.C.) and standard references (Corbet, 1999 Silsby, 2001). The phylogenetic pattern in the evolution of integumentary blue was estimated using a recent and comprehensive phylogeny of the odonates(Rehn, 2003). The estimated number of evolutionary events to describe that diversity was calculated using MacClade 4 (Maddison and Maddison,2000).


Dragonflies: Ancient and Aggressive Insect Aviators

Imagine an underwater world where bloodthirsty babies are the thing everyone fears most. These children lie in ambush for their prey or roam the landscapes like coyotes in search of their next meal. They're cunning, aggressive, efficient predators, but when they grow up they leave the water to terrorize land dwellers with the same homicidal verve that characterized their younger years. Also, their mating rituals involve a lot of strange, acrobatic sex.

This sounds like the plot of a gripping sci-fi movie, and if the babies and adults in question were human (or human-ish), it totally would be. But this world really does exist — it exists in the world of the dragonfly.

Dragonfly Math

"They're powerful, fast predators," says Giff Beaton, the author of "Dragonflies and Damselflies of Georgia and the Southeast." "The underwater nymphs are just as powerful and efficient killers as the free-flying adults. They have a fascinating lifecycle biology, and are incredibly beautiful: there are brown ones, orange ones, red ones, blue ones, green ones. They're gorgeous — just spectacularly colorful."

Adult dragonflies will eat things as large as themselves. They can fly up to 30 miles (48 kilometers) per hour and have unbelievably sharp eyes — they can identify a potential prey, predator, mate or rival from around 100 feet (30 meters) away.

"When they see a potential prey item, they don't just chase it — they can calculate what the prey is, what direction it's flying in and what speed, and they move on an intercept course to get it. They're one of the only insects that can predict where their prey will wind up, and they'll head it off. They're doing trigonometry in their heads — it's so cool."

Ancient Insects

It would be unfair to go on and on about dragonflies (suborder Anisoptera) alone when they share so many characteristics with their close cousins, the damselflies (suborder Zygoptera). They look very similar, but dragonflies have large eyes and hold their wings out like airplanes when resting, whereas damselflies have small eyes and hold their wings straight up above their bodies.

Together, modern dragonflies and damselflies make up an order of insects called Odonata, which just means "tooth" in Greek. They're certainly not the only insects with toothed mandibles, but there's something of a "the first" vibe about them. They're almost unimaginably old: Something that looks like a dragonfly or a damselfly has been around for about 325 million years. For instance, the griffinfly — the largest-known insect ever to buzz around this bonkers planet — grew to 30 inches (76 centimeters) wide, and emerged out of the first forests of the Carboniferous period.

"Their wing venation and body plan is very, very close to the dragonflies we see today," says Beaton. "Odonates are effectively unchanged since then, which tells you how effective their life cycle and body style actually is."

Longterm Babies

There are over 5,000 species of odonates in the world, on every continent except Antarctica, and most of them spend a lot of their lives as babies.

"Some spend up to 90 percent of their life as nymphs, almost always underwater," says Beaton. "Some species can stay nymphs for up to five years."

But just because they're youngsters doesn't mean they're harmless.

"Some hide under the substrate or roots and breathe out of a little tube — they're ambush predators others walk around stalking prey a couple species in the world actually leave the water and walk around on land, attacking anything they can find."

Acrobatic Mating

As with many animals, female odonates don't need to worry much about finding a male to mate with. When she's ready, she just makes her way to the water where the males are waiting, defending the most luxurious territories where the habitat is best. For some species, that might mean there's a special plant that the female likes to lay eggs on, or a particular water temperature or pH. Some species only breed in streams, and others just in ponds — the variables may differ but the males always take it extremely seriously.

When a female finds a satisfactory male, he holds on to a place behind her head with some little claspers on his abdomen and they fly around together connected, in a position called "tandem." Nothing has actually happened yet — this is just the romance part. The male then transfers his sperm (little packets of sex cells called spermatophores) from the ninth segment of his body to his second segment. Once he's done that, things get acrobatic: The female then has to bend her abdomen under to connect the tip of her abdomen (where the eggs are) to his second segment, where he's just put his spermatophores. The resulting shape is called the "wheel" or "heart" position.

"This is where it gets unique," says Beaton. "The male doesn't just fertilize her at this point — he checks first to see if she has mated with other males, and he'll spend a considerable amount of time trying to scoop the spermatophores from other males out, just to make sure he's the one that fertilizes her eggs. No other insects do this, although the behaviour has been observed in a few spiders."

For the female odonates, a single fertilization is enough to fertilize all her eggs for her entire reproductive life, which is usually only a month or two. But once she's mated with one male, she'll try to find another. The first male knows this, so he'll often try to remain connected to her, which is called 'contact guarding,' or just hover threateningly above her while she lays her eggs to make sure no other male swoops in.

Yes, it's aggressive. But as they say, how you do anything is how you do everything.

In ancient times, Japanese warriors decorated their helmets with dragonfly motifs because they were thought to be invincible.


Identification

Review the images for tips on how to identify these predators.

Adults

Adults have two distinctive spots on the top of their thoraxes, as well as a keyhole-shaped marking on their backs. Head and legs are black, with a stripe on the latter. Colors of thorax and abdomen are variable, with black markings on either red, orange or tan background ‘shoulders’ are rounded in contrast to the spines seen in other predatory stink bugs. Like all predatory stink bugs, Twospotted stink bugs have beaks that are at least twice as thick as their antennae (see a comparison).

Nymphs

No wings. Beaks like adults. The overall shape is rounded with a somewhat flattened underside. Black or brown head, thorax, and legs. Abdomen with red, orange or tan O shape, and black spots around edge.


Mimicry makes animals to evolve!

Mimicry is one of the processes that makes animals to evolve faster (do you want to learn more about evolutionary processes? Enter this link!).

These changes may occur in a higher or lower speed. So, what about those animals that mimic other organisms? Mimetic animals are in constant selective pressure to look more like their models in order to go unnoticed and improve their survival, but at the same time imitated organisms (the models) are also under selection to sharp their ability to discern between models and imitators .

Thus, mimicry is an incredible evolutionary engine: a perpetual struggle between mimetic organisms and imitated ones in order to improve their respective survivals.