Dragonfly

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Dragonfly
Yellow-winged Darter
Scientific classification
Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Odonata Suborder: Epiprocta Infraorder: Anisoptera Selys, 1854
Families
Aeshnidae Austropetaliidae Cordulegastridae Corduliidae Gomphidae Libellulidae Macromiidae Neopetaliidae Petaluridae

A dragonfly is an insect belonging to the order Odonata, the suborder Epiprocta or, in the strict sense, the infraorder Anisoptera. It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body.

Dragonflies typically eat mosquitoes, midges and other small insects like flies, bees, and butterflies. They are usually found around lakes, ponds, streams, and wetlands because their larvae, known as "nymphs", are aquatic. Dragonflies do not normally bite or sting humans (though they will bite in order to escape, for example, if grasped by the abdomen); in fact, they are valued as a predator that helps control the populations of harmful insects, such as mosquitoes. It is because of this that dragonflies are sometimes called "mosquito hawks" in North America along with the Crane Fly^{[citation needed]} (which, in fact, does not eat mosquitoes).

Contents 1 Life cycle 2 General facts 2.1 Record breakers 2.2 Vision 2.3 Camouflage 3 Classification 3.1 Ancient dragonflies ("Anisozygoptera") 3.2 Dragonflies vs. damselflies 4 Some common species of the Northern Hemisphere 5 Some common species of the Southern Hemisphere 6 Dragonflies in culture 7 Gallery 8 References 9 See also 10 External links

[edit] Life cycle

Female dragonflies lay eggs in or near water, often in or on floating or emergent plants. Most of the life of the dragonfly is spent in the larval (naiad, aka nymph) form, beneath the water surface, using internal gills to breathe, and catching other invertebrates or even vertebrates such as tadpoles and fish. In the adult (flying) stage, larger species of dragonfly can live as long as four months.

[edit] General facts

[edit] Record breakers

Much larger dragonfly species existed in the distant past than occur on earth today. The largest one, found as a fossil, is an extinct Protodonata named Meganeura monyi from the Permian period with a wingspan of 70–75 cm (27.5–29.5 in). This compares to 19 cm (7.5 in) for the largest modern species of odonates, the Hawaiian endemic dragonfly, Anax strenuus. The smallest modern species recorded is the libellulid dragonfly, Nannophya pygmaea from East Asia with a wingspan of only 20 mm, or about ¾ of an inch.

Dragonflies are the world's fastest insects and, although estimates of their speed vary wildly, most credible authorities say they are capable of reaching speeds of between 30 and 60 km/h (19 to 38 mph).^[1] A study showed that dragonflies can travel as much as 137 km (85 mi) in one day.^[2]

[edit] Vision

Dragonflies have excellent eyesight due to their eye structure. Their compound eyes have up to 30,000 facets, each of which is a separate light-sensing organ or ommatidium, arranged to give nearly a 360° field of vision.

[edit] Camouflage

It was recently discovered that dragonflies employ a particular optical illusion, termed motion camouflage^[3], to stalk other insects that invade their territory. The research suggests that a dragonfly can move in such a way as to project itself as a stationary object while speedily attacking its victims. These findings illustrate for the first time how dragonflies use complex camouflaging techniques during aerial combat.

[edit] Classification

[edit] Ancient dragonflies ("Anisozygoptera")

Conventionally, the Anisoptera were given suborder rank beside the ancient dragonflies ("Anisozygoptera", two living species and numerous fossil ones), but it has been determined recently that the Anisozygoptera form a paraphyletic assemblage of primitive relatives of the Anisoptera. Thus, the Anisoptera are reduced to an infraorder, forming the new suborder Epiprocta (dragonflies in a general sense). The artificial grouping Anisozygoptera is disbanded, its members being recognized as largely extinct offshoots at various stages of dragonfly evolution.

The oldest known species of dragonfly is the 320 million year old Delitzschala bitterfeldensis. Another old genus is Namurotypus.

[edit] Dragonflies vs. damselflies

Damselflies (Suborder Zygoptera) are often confused with dragonflies, but the two insects are distinct: most damselflies at rest hold their wings together above the body or held slightly open above (such as in the family Lestidae), whereas dragonflies at rest hold their wings horizontally or occasionally slightly down and forward. Also, the hindwing of the dragonfly broadens near the base, caudal to the connecting point at the body, while the hindwing of the damselfly is essentially similar to the forewing. The eyes on a damselfly are separated; in most dragonflies the eyes touch, with notable exceptions to this being in the Petaluridae (Petaltails) and the Gomphidae (Clubtails). Both are members of the Odonata, making their life cycles similar.

[edit] Some common species of the Northern Hemisphere

Emperor, Anax imperator Keeled Skimmer, Orthetrum coerulescens Black-tailed Skimmer, Orthetrum cancellatum Common Whitetail, Libellula lydia Migrant Hawker, Aeshna mixta Azure Hawker, Aeshna caerulea Southern Hawker, Aeshna cyanea Norfolk Hawker, Aeshna isosceles Common Hawker, Aeshna juncea Red-veined Darter, Sympetrum fonscolombii Common Darter, Sympetrum striolatum Vagrant Darter, Sympetrum vulgatum

Yellow-winged Darter, Sympetrum flaveolum Broad-bodied Chaser, Libellula depressa Four-spotted Chaser, Libellula quadrimaculata Scarce Chaser, Libellula fulva Green Darner, Anax junius Downy Emerald, Cordulia aenea Blue-eyed Darner, Aeshna multicolor Roseate Skimmer, Orthemis ferruginea Widow Skimmer, Libellula luctuosa Great Pondhawk, Erythemis vesiculosa Comet Darner, Anax longipes Banded Pennant, Celithemis fasciata

[edit] Some common species of the Southern Hemisphere

Glistening Demoiselle Phaon iridipennis Dancing Jewel Platycypha caligata Mountain Malachite Chlorolestes fasciatus Common Spreadwing Lestes plagiatus Common Threadtail Elattoneura glauca Goldtail Allocnemis leucosticta Swamp Bluet Africallagma glaucum Pinhey's Whisp Agriocnemis pinheyi Black-tailed Bluet Azuragrion nigridorsum Common Citril Ceriagrion glabrum Yellow-faced Sprite Pseudagrion citricola Gambel's Sprite Pseudagrion gamblesi Hagen's Sprite Pseudagrion hageni

Hamon's Sprite Pseudagrion hamoni Kersten's Sprite Psuedagrion kersteni Masai Sprite Pseudagrion massaicum Salisbury Sprite Pseudagrion salisburyense Natal Sprite Pseudagrion spernatum Orange Emperor Anax speratus Common Thorntail Ceratogomphus pictus Tigertail Ictinogomphus ferox Yellowjack Notogomphus praetorius Rock Hooktail Paragomphus cognatus Pintail Acisoma panorpoides Banded Groundling Brachythemis leucosticta Broad Scarlet Crocothemis erythraea

Little Scarlet Crocothemis sanguinolenta Black Percher Diplacodes lefebvrii Black-tailed Skimmer Nesciothemis farinosa Two-striped Skimmer Orthetrum caffrum Epaulet Skimmer Orthetrum chrysostigma Julia Skimmer Orthetrum julia St. Lucia Widow Palpopleura portia Nomad Sympetrum fonscolombii Red-veined Dropwing Trithemas arteriosa Navy Dropwing Trithemis furva Kirby's Dropwing Trithemis kirbyi Jaunty Dropwing Trithemis stictica

[edit] Dragonflies in culture

In Europe, dragonflies have often been viewed as sinister. Some English vernacular names, such as "devil's needle" and "ear cutter", link them with evil or injury.^[4] A Romanian folk tale says that the dragonfly was once a horse possessed by the devil, and Swedish folklore holds that the devil uses dragonflies to weigh people's souls.^[5] Another Swedish legend holds that trolls use the dragonflies as spindles when weaving their clothes (hence the Swedish word for dragonfly trollslända, lit. "troll's spindle") as well as sending them to poke out the eyes of their enemies.^{[citation needed]} The Norwegian name for dragonflies is "Øyenstikker", which literally means Eye Poker. They are often associated with snakes, as in the Welsh name gwas-y-neidr, "adder's servant".^[4] The Southern United States term "snake doctor" refers to a folk belief that dragonflies follow snakes around and stitch them back together if they are injured.^[6] The Lithuanian word "Laumžirgis" is a composite word meaning "the Lauma's horse", while in Dutch, Aeshna mixta is called "Paardenbijter" or "horse biter". In some South American countries, dragonflies are also called matacaballo (horse killer), or caballito del diablo (devil's horse), since they were perceived as harmful, some species being quite large for an insect.

In East Asia and among Native Americans, dragonflies have a far better reputation, one that can also be said to have positively influenced modern day views about dragonflies in most countries.

For some Native American tribes they represent swiftness and activity, and for the Navajo they symbolize pure water. Dragonflies are a common motif in Zuni pottery; stylized as a double-barred cross, they appear in Hopi rock art and on Pueblo necklaces.^[7] It is said in some Native American beliefs that dragonflies are a symbol of renewal after a time of great hardship.

In Japan dragonflies are symbols of courage, strength, and happiness, and they often appear in art and literature, especially haiku. In ancient mythology, Japan was known as Akitsushima, which means "Land of the Dragonflies". The love for dragonflies is reflected by the fact that there are traditional names for almost all of the 200 species of dragonflies found in and around Japan.^[8] 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.^[9]

They also have traditional uses as medicine in Japan and China. In some parts of the world they are a food source, eaten either as adults or larvae; in Indonesia, for example, they are caught on poles made sticky with birdlime, then fried in oil as a delicacy.^[4]

Images of dragonflies were common in Art Nouveau, especially in jewelry designs.^[10] They have also been used as a decorative motif on fabrics and home furnishings.^[11]

[edit] Gallery

Australian Blue Dragonfly	Green Darner Dragonfly feeding on honeybee	Austrogomphus guerini	Ruby Meadowhawk dragonfly, Sympetrum rubicundulum
Dragonfly in midflight over a creek	The compound eyes of a dragonfly	Cherry-faced Meadowhawk, Sympetrum internum	Dragonflies mating
mating	mating	Dragonfly depositing eggs	Dragonfly nymph
Dragonfly from Lower Silesia (Poland) - bottom	Dragonfly from Lower Silesia - top