page_title: Dragonfly
section_title: General description
hierarchical_section_title: Dragonfly / General description
caption_attribution_description: Name Ischnura senegalensis Family Coenagrionidae English: Common Bluetail, a widespread damselfly in Africa, the Middle East, Southern and Eastern Asia. Français&#160;: Ischnura senegalensis, une Demoiselle très commune en Afrique, dans le Moyen Orient, en Asie du Sud et de l'Est. 日本語: アオモンイトトンボ Polski: Ischnura senegalensis - gatunek ważki z rodziny łątkowatych (Coenagrionidae) Português: Ischnura senegalensis, uma libélula muito comum em África, no Médio Oriente e no sul e este da Ásia. Camera Details: Camera: PENTAX K10D Lens: TAMRON SP AF90mm F/2.8 Di (Model272E)
context_page_description: A dragonfly is an insect belonging to the order Odonata, infraorder Anisoptera. Adult dragonflies are characterized by large, multifaceted eyes, two pairs of strong, transparent wings, sometimes with coloured 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 the 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 colours 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 750 mm. There are about 3,000 extant species. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threatens dragonfly populations around the world.
context_section_description: Dragonflies (suborder Anisoptera) are heavy-bodied, strong-flying insects that hold their wings horizontally both in flight and at rest. By contrast, damselflies (suborder Zygoptera) have slender bodies and fly more weakly; most species fold their wings over the abdomen when stationary, and the eyes are well separated on the sides of the head.
  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 22650 ommatidia of two varying sizes, 4500 being large. The facets facing downward tend to be smaller. Petalura gigantea has 23890 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.
  The thorax consists of three segments as in all insects. The prothorax is small and is flattened dorsally into a shield-like disc which has two transverse ridges. The mesothorax and metathorax are fused into a rigid, box-like structure with internal bracing, and provides a robust attachment for the powerful wing muscles inside it. The thorax bears two pairs of wings and three pairs of legs. The wings are long, veined, and membranous, narrower at the tip and wider at the base. The hindwings are broader than the forewings and the venation is different at the base. The veins carry haemolymph, which is analogous to blood in vertebrates and carries out many similar functions, but which also serves a hydraulic function to expand the body between nymphal stages (instars) and to expand and stiffen the wings after the adult emerges from the final nymphal stage. The leading edge of each wing has a node where other veins join the marginal vein, and the wing is able to flex at this point. In most large species of dragonflies, the wings of females are shorter and broader than those of males. The legs are rarely used for walking, but are used to catch and hold prey, for perching, and for climbing on plants. Each has two short basal joints, two long joints, and a three-jointed foot, armed with a pair of claws. The long leg joints bear rows of spines, and in males, one row of spines on each front leg is modified to form an "eyebrush", for cleaning the surface of the compound eye.
  The abdomen is long and slender and consists of 10 segments. There are three terminal appendages on segment 10; a pair of superiors (claspers) and an inferior. The second and third segments are enlarged, and in males, on the underside of the second segment has a cleft, forming the secondary genitalia consist of lamina, hamule, genital lobe and penis. There are remarkable variations in the presence and the form of the penis and the related structures, the flagellum, cornua and genital lobes. Sperm is produced at the 9th segment and is transferred to the secondary genitalia prior to mating. The male holds the female behind the head using a pair of claspers on the terminal segment. In females, the genital opening is on the underside of the eighth segment and is covered by a simple flap (vulvar lamina) or an ovipositor, depending on species and the method of egg-laying. Dragonflies having simple flap shed the eggs in water, mostly in flight. Dragonflies having ovipositor, use it to puncture soft t
caption: Damselflies, like this Ischnura senegalensis, are slenderer in build than dragonflies, and most hold their wings closed over their bodies.
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