I often see décor on empty open spaces on the front of houses — sunbursts, beautiful curlicue designs, Texas stars, etc. Today, there is a dragonfly, first one I have seen on the front of a home. Even though it is large, it is quite ethereal in appearance. The delicate, sculptured wings look like they could come together and take me soaring at any moment, if only I could shrink down enough to fit on the dragonfly’s back. Unlike the lowly housefly, dragonflies have an elegant, almost transcendent quality. Their iridescent wings that shimmer in the sunlight are part of the magic. Because they shine, they are often replicated in shiny objects like jewelry, paperweights, Christmas ornaments, etc. In fact, I have a lovely red & gold dragonfly Christmas ornament that was a gift. I have also given a gift of dragonfly earrings. Plus a friend of mine’s sister got a dragonfly tattoo to camouflage a surgery scar. You never can tell where they’re going to turn up. Let’s find out more about them.
According to Wikipedia, a dragonfly is an insect belonging to the order Odonata, infraorder Anisoptera — from Greek "unequal" and "wing", because the hindwing is broader than the forewing. Adult dragonflies are characterized by large, multifaceted eyes; two pairs of strong, transparent wings, sometimes with colored patches; and an elongated body. Dragonflies can be mistaken for the related group, damselflies, which are similar in structure, though usually lighter in build; however, the wings of most dragonflies are held flat and away from the body, while damselflies hold their wings folded at rest, along or above the abdomen. Dragonflies are agile fliers, while damselflies have a weaker, fluttery flight. Many dragonflies have brilliant iridescent or metallic colors produced by structural coloration, making them conspicuous in flight. An adult dragonfly's compound eyes have nearly 24,000 ommatidia each.
Fossils of very large dragonfly ancestors in the Protodonata are found from 325 million years ago in Upper Carboniferous rocks; these had wingspans up to about 30 inches. About 3,000 extant species are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threatens dragonfly populations around the world.
Dragonflies are predators, both in their aquatic larval stage — when they are known as nymphs or naiads — and as adults. In some species, the nymphal stage lasts for up to five years, and the adult stage may be as long as ten weeks, but most species have an adult lifespan in the order of five weeks or less, and some survive for only a few days. They are fast, agile fliers, sometimes migrating across oceans, and often live near water. They have a uniquely complex mode of reproduction involving indirect insemination, delayed fertilization and sperm competition. During mating, the male grasps the female at the back of the head, and the female curls her abdomen under her body to pick up sperm from the male's secondary genitalia at the front of his abdomen, forming the "heart" or "wheel" posture.
Dragonflies are represented in human culture on artifacts such as pottery, rock paintings, statues and Art Nouveau jewelery. They are used in traditional medicine in Japan and China and caught for food in Indonesia. They are symbols of courage, strength and happiness in Japan, but seen as sinister in European folklore. Their bright colors and agile flight are admired in the poetry of Lord Tennyson and the prose of H.E. Bates.
Phylogeny Dragonflies and their relatives are an ancient group. The oldest fossils are of the Protodonata from the 325 million years ago Upper Carboniferous of Europe, a group that included the largest insect that ever lived — Meganeuropsis permiana from the Early Permian — with a wingspan around 30 inches; their fossil record ends with the Permian-Triassic extinction event about 247 million years ago. The Protanisoptera — another ancestral group that lacks certain wing vein characters found in modern Odonata — lived from the Early to Late Permian age until the end Permian event and are known from fossil wings from current-day United States, Russia and Australia, suggesting they might have been cosmopolitan in distribution. The forerunners of modern Odonata are included in a clade called the Panodonata, which include the basal Zygoptera or damselflies and the Anisoptera or true dragonflies. Today, some 3,000 species are extant around the world.
Aeshnidae The Aeshnidae — also called aeshnids, hawkers or darners — is a family of dragonflies. The family includes the largest dragonflies found in North America and Europe and among the largest dragonflies on the planet.
Gomphidae The Gomphidae are a family of dragonflies commonly referred to as clubtails or club-tailed dragonflies. The family contains about 90 genera and 900 species found across North and South America, Europe, Asia and Australia. The name refers to the club-like widening of the end of the abdomen — abdominal segments 7 through 9. However, this club is usually less pronounced in females and is entirely absent in some species.
Corduliidae The Corduliidae — also known as the emeralds, emerald dragonflies or green-eyed skimmers — is a family of dragonflies. These dragonflies are usually black or dark brown with areas of metallic green or yellow, and most of them have large, emerald-green eyes. The larvae are black, hairy-looking and usually semiaquatic. This family include species called "baskettails," "emeralds," "sundragons," "shadowdragons" and "boghaunters." They are not uncommon and are found nearly worldwide, but some individual species are quite rare. Hine’s emerald dragonfly ‒ Somatochlora hineana, for example, is an endangered species in the United States.
Libellulidae The skimmers or perchers and their relatives form the Libellulidae, the largest dragonfly family in the world. It is sometimes considered to contain the Corduliidae as the subfamily Corduliinae and the Macromiidae as the subfamily Macromiinae. Even if these are excluded, there still remains a family of over 1,000 species. With nearly worldwide distribution, these are almost certainly the most often seen of all dragonflies.
The genus Libellula is mostly New World, but also has one of the few endangered odonates from Japan: Libellula angelina. Many of the members of this genus are brightly colored or have banded wings. The related genus Plathemis includes the whitetails. The genus Celithemis contains several brightly marked species in the southern United States. Members of the genus Sympetrum are called darters or meadowhawks in North America and are found throughout most of the world, except Australia. Several Southern Hemisphere species in the genera Trithemis and Zenithoptera are especially beautiful. Other common genera include Tramea and Pantala.
The libellulids have stout-bodied larvae with the lower lip or labium developed into a mask over the lower part of the face.
Macromiidae The insect family Macromiidae contains the dragonfly species known as cruisers or skimmers. They tend to fly over bodies of water and roads straight down the middle. They are similar to Aeshnidae in size, but the eyes are green and just barely meet at the top of the head.
Macromiidae or Macromiinae has been traditionally considered as a subfamily of Corduliidae. It contains four genera and 125 species worldwide.
Females of this family lack an ovipositor at the end of the abdomen and lay their eggs by dipping the abdomen in the water as they fly over. Ovipositing is usually done without a male.
Naiads are found in rivers, streams and lakes where there is water movement. They crawl in debris at the water's bottom and wait for prey.
Distribution Dragonflies live on every continent except Antarctica. In contrast to the damselflies, which tend to have restricted distributions, some genera and species are spread across continents. For example, the blue-eyed darner Rhionaeschna multicolor lives all across North America and in Central America; emperors Anax live throughout the Americas from as far north as Newfoundland to as far south as Bahia Blanca in Argentina, across Europe to central Asia, North Africa and the Middle East. The globe skimmer Pantala flavescens is probably the most widespread dragonfly species in the world; it is cosmopolitan, occurring on all continents in the warmer regions. Most Anisoptera species are tropical, with far fewer species in temperate regions.
Some dragonflies — including libellulids and aeshnids — live in desert pools, for example in the Mojave Desert, where they are active in shade temperatures between 64.4 to 113 °F; these insects were able to survive body temperatures above the thermal death point of insects of the same species in cooler places.
Dragonflies live from sea level up to the mountains, decreasing in species diversity with altitude. Their altitudinal limit is about 3,700 meters, represented by a species of Aeshna in the Parmirs, a mountain range between Central Asia, South Asia and East Asia, at the junction of the Himalayas with the Tian Shan, Karakoram, Kunlun and Hindu Kush. They are among the world's highest mountains.
Dragonflies become scarce at higher latitudes. They are not native to Iceland, but individuals are occasionally swept in by strong winds, including a vagrant emperor or Hernianax ephippiger native to North Africa and an unidentified darter species. In Kamchatka, only a few species of dragonfly including the treeline emerald Somatochlora arctica and some aeshnids such as Aeshna subarctica are found, possibly because of the low temperature of the lakes there. The treeline emerald also lives in northern Alaska, within the Arctic Circle, making it the most northerly of all dragonflies.
General description An adult dragonfly has three distinct segments, the head, thorax and abdomen — as in all insects. It has a chitinous exoskeleton of hard plates held together with flexible membranes. The head is large with very short antennae. It is dominated by the two compound eyes, which cover most of its surface. The compound eyes are made up of ommatidia, the numbers being greater in the larger species. Aeshna interrupta has 22,650 ommatidia of two varying sizes, 4,500 being large. The facets facing downward tend to be smaller. Petalura gigantea has 23,890 ommatidia of just one size. These facets provide complete vision in the frontal hemisphere of the dragonfly. The compound eyes meet at the top of the head — except in the Petaluridae and Gomphidae, as also in the genus Epiophlebia. Also, they have three simple eyes or ocelli. The mouthparts are adapted for biting with a toothed jaw; the flap-like labrum, at the front of the mouth, can be shot rapidly forward to catch prey. The head has a system for locking it in place that consists of muscles and small hairs on the back of the head that grip structures on the front of the first thoracic segment. This arrester system is unique to the Odonata and is activated when feeding and during tandem flight.
Coloration Many adult dragonflies have brilliant iridescent or metallic colors produced by structural coloration, making them conspicuous in flight. Their overall coloration is often a combination of yellow, red, brown and black pigments, with structural colors. Blues are typically created by microstructures in the cuticle that reflect blue light. Greens often combine a structural blue with a yellow pigment. Freshly emerged adults — known as tenerals — are often pale-colored and obtain their typical colors after a few days, some have their bodies covered with a pale blue, waxy powderiness called pruinosity; it wears off when scraped during mating, leaving darker areas.
Some dragonflies, such as the green darner, Anax junius, have a noniridescent blue that is produced structurally by scatter from arrays of tiny spheres in the endoplasmic reticulum of epidermal cells underneath the cuticle.
The wings of dragonflies are generally clear, apart from the dark veins and pterostigmata. In the chasers or Libellulidae, however, many genera have areas of color on the wings: for example, groundlings (Brachythemis) have brown bands on all four wings, while some scarlets (Crocothemis) and dropwings (Trithemis) have bright orange patches at the wing bases. Some aeshnids such as the brown hawker or Aeshna grandis have translucent, pale yellow wings.
Habitats Dragonflies as a group occupy a considerable variety of habitats, but many species, and some families, have their own specific environmental requirements. Some species prefer flowing waters, while others prefer standing water. For example, the Gomphidae clubtails live in running water, and the Libellulidae skimmers live in still water. Some species live in temporary water pools and are capable of tolerating changes in water level, desiccation and the resulting variations in temperature, but some genera such as Sympetrum darters have eggs and larvae that can resist drought and are stimulated to grow rapidly in warm, shallow pools, also often benefiting from the absence of predators there. Vegetation and its characteristics including submerged, floating, emergent or waterside are also important. Adults may require emergent or waterside plants to use as perches; others may need specific submerged or floating plants on which to lay eggs. Requirements may be highly specific, as in Aeshna viridis green hawker, which lives in swamps with the water-soldier, Stratiotes aloides. The chemistry of the water, including its trophic status — degree of enrichment with nutrients — and pH can also affect its use by dragonflies. Most species need moderate conditions, not too europhic, not too acid; a few species such as Sympetrum danae black darter and Libellula quadrimaculata four-spotted chaser prefer acidic waters such as peat bogs, while others such as Libellula fulva scarce chaser need slow-moving, eutrophic waters with reeds or similar waterside plants.
Flight Dragonflies are powerful and agile fliers, capable of migrating across the sea, moving in any direction and changing direction suddenly. In flight, the adult dragonfly can propel itself in six directions: upward, downward, forward, backward, to left and to right. They have four different styles of flight: A number of flying modes are used that include counter-stroking, with forewings beating 180° out of phase with the hindwings, is used for hovering and slow flight. This style is efficient and generates a large amount of lift; phased-stroking, with the hindwings beating 90° ahead of the forewings, is used for fast flight. This style creates more thrust, but less lift than counter-stroking; synchronized-stroking, with forewings and hindwings beating together, is used when changing direction rapidly, as it maximizes thrust; and gliding, with the wings held out, is used in three situations: free gliding, for a few seconds in between bursts of powered flight; gliding in the updraft at the crest of a hill, effectively hovering by falling at the same speed as the updraft; and in certain dragonflies such as darters, when "in cop" with a male, the female sometimes simply glides while the male pulls the pair along by beating his wings.
The wings are powered directly, unlike most families of insects, with the flight muscles attached to the wing bases. Dragonflies have a high power/weight ratio and have been documented accelerating at 4 G linearly and 9 G in sharp turns while pursuing prey.
Dragonflies generate lift in at least four ways at different times, including classical lift like an aircraft wing; supercritical lift with the wing above the critical angle, generating high lift and using very short strokes to avoid stalling; and creating and shedding vortices. Some families appear to use special mechanisms, as for example the Libellulidae which take off rapidly, their wings beginning pointed far forward and twisted almost vertically. Dragonfly wings behave highly dynamically during flight, flexing and twisting during each beat. Among the variables are wing curvature, length and speed of stroke, angle of attack, forward/back position of wing, and phase relative to the other wings.
Feeding Adult dragonflies hunt on the wing using their exceptionally acute eyesight and strong, agile flight. They are almost exclusively carnivorous, eating a wide variety of insects ranging from small midges and mosquitoes to butterflies, moths, damselflies and smaller dragonflies. A large prey item is subdued by being bitten on the head and is carried by the legs to a perch. Here, the wings are discarded and the prey usually ingested head first. A dragonfly may consume as much as a fifth of its body weight in prey per day. Dragonflies are also some of the insect world's most efficient hunters, catching up to 95% of the prey they pursue. The larvae are voracious predators, eating most living things that are smaller than they are. Their staple diet is mostly bloodworms and other insect larvae, but they also feed on tadpoles and small fish. A few species, especially those that live in temporary waters, are likely to leave the water to feed. Nymphs of Cordulegaster bidentata sometimes hunt small arthropods on the ground at night, while some species in the Anax genus have even been observed leaping out of the water to attack and kill full-grown tree frogs.
Predators and parasites Although dragonflies are swift and agile fliers, some predators are fast enough to catch them. These include falcons such as the American kestrel, merlin and hobby; nighthawks, swifts, flycatchers and swallows also take some adults; some species of wasps, too, prey on dragonflies, using them to provision their nests, laying an egg on each captured insect. In the water, various species of ducks and herons eat dragonfly larvae, and they are also preyed on by newts, frogs, fish and water spiders. Amur falcons — which migrate over the Indian Ocean at a period that coincides with the migration of the globe skimmer dragonfly Pantala flavescent — may actually be feeding on them while on the wing.
Dragonflies are affected by three major groups of parasites: water mites, gregarine protozoa and trematode flatworms or flukes. Water mites, Hydracarina, can kill smaller dragonfly larvae and may also be seen on adults. Gregarines infect the gut and may cause blockage and secondary infection. Trematodes are parasites of vertebrates such as frogs, with complex life cycles often involving a period as a stage called a cercaria in a secondary host, a snail. Dragonfly nymphs may swallow cercariae, or these may tunnel through a nymph's body wall; they then enter the gut and form a cyst or metacercaria, which remains in the nymph for the whole of its development. If the nymph is eaten by a frog, the amphibian becomes infected by the adult or fluke stage of the trematode.
In culture Many Native American tribes consider dragonflies to be medicine animals that have special powers. For example, the southwestern tribes, including the Pueblo, Hopi and Zuni, associated dragonflies with transformation. They referred to dragonflies as "snake doctors" because they believed dragonflies followed snakes into the ground and healed them if they were injured. For the Navajo, dragonflies symbolize pure water. Often stylized in a double-barred cross design, dragonflies are a common motif in Zuni pottery, as well as Hopi rock art and Pueblo necklaces.
As a seasonal symbol in Japan, the dragonflies are associated with season of autumn. In Japan, they are symbols of rebirth, courage, strength and happiness. They are also depicted frequently in Japanese art and literature, especially haiku poetry. Japanese children catch large dragonflies as a game, using a hair with a small pebble tied to each end, which they throw into the air. The dragonfly mistakes the pebbles for prey, gets tangled in the hair and is dragged to the ground by the weight.
Among the classical names of Japan are Akitsukuni, Akitsushima and Toyo-akitsushima. Akitu is an old word for dragonfly, so one interpretation of Akitsushima is "Dragonfly Island." This is attributed to a legend in which Japan's mythical founder, Emperor Jimmu, was bitten by a mosquito, which was then eaten by a dragonfly.
In Chinese culture, dragonflies symbolize both change and instability. They are also symbols in the Chinese practices of feng shui, where placements of dragonfly statues and artwork in parts of a home or office are believed to bring new insights and positive changes.
In both China and Japan, dragonflies have been used in traditional medicine. In Indonesia, adult dragonflies are caught on poles made sticky with birdlime, then fried in oil as a delicacy.
Images of dragonflies are common in Art Nouveau, especially in jewelery designs. They have also been used as a decorative motif on fabrics and home furnishings.
Douglas, a British motorcycle manufacturer based in Bristol, named its innovatively designed postwar 350-cc flat-twin model the Dragonfly.
In Europe, dragonflies have often been seen as sinister. Some English vernacular names, such as "horse-stinger," "devil's darning needle" and "ear cutter" link them with evil or injury. Swedish folklore holds that the devil uses dragonflies to weigh people's souls. The Norwegian name for dragonflies is Øyenstikker or "eye-poker," and in Portugal, they are sometimes called tira-olhos or "eyes-snatcher." They are often associated with snakes, as in the Welsh name gwas-y-neidr, "adder's servant." The southern United States terms "snake doctor" and "snake feeder" refer to a folk belief that dragonflies catch insects for snakes or follow snakes around and stitch them back together if they are injured. Interestingly, the Hungarian name for dragonfly is szitakötő or "sieve-knitter."
The watercolorist Moses Harris (1731–1785), known for his “The Aurelian or natural history of English insects” in 1766, published in 1780, the first scientific descriptions of several Odonata including the banded demoiselle, Calopteryx splendens. He was the first English artist to make illustrations of dragonflies accurate enough to be identified to species — Aeshna grandis at top left of plate illustrated — though his rough drawing of a larva at lower left with the mask extended appears to be plagiarized.
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