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74-578: The unit was envisioned as a miniaturized four-winged ornithopter which uses a flight model based on that of a dragonfly . It was the first palm sized miniaturized ornithopter to be prototyped to exhibit powerful actuation at small sizes, though other larger versions have been developed. (e.g., the DelFly ), the Dragonfly was the first to make use of multiple models, each customizable with multiple options, such as wifi connectivity. The Dragonfly UAV built off

148-464: A Hemianax 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

222-435: A cornea , lens , and photoreceptor cells which distinguish brightness and color. The image perceived by this arthropod eye is a combination of inputs from the numerous ommatidia, which are oriented to point in slightly different directions. Compared with single-aperture eyes , compound eyes have poor image resolution ; however, they possess a very large view angle and the ability to detect fast movement and, in some cases,

296-631: A reed or other emergent plant, and moults ( ecdysis ). Anchoring itself firmly in a vertical position with its claws, its exoskeleton begins to split at a weak spot behind the head. The adult dragonfly crawls out of its nymph exoskeleton , the exuvia , arching backwards when all but the tip of its abdomen is free, to allow its exoskeleton to harden. Curling back upwards, it completes its emergence, swallowing air, which plumps out its body, and pumping haemolymph into its wings, which causes them to expand to their full extent. Dragonflies in temperate areas can be categorized into two groups: an early group and

370-434: A bit far-fetched", and cited it as "the latest example of how consumers need to be more careful with crowdfunding". Veckans Affärer described the Dragonfly as "too good to be true", and described it and Pirate3D's Buccaneer 3D printer as part of a trend of crowdfunding projects that had not delivered on their promises. Dragonfly A dragonfly is a flying insect belonging to the infraorder Anisoptera below

444-409: A branchial chamber, located around the fourth and fifth abdominal segments. These internal gills consist originally of six longitudinal folds, each side supported by cross-folds. But this system has been modified in several families. Water is pumped in and out of the abdomen through an opening at the tip. The naiads of some clubtails ( Gomphidae ) that burrow into the sediment, have a snorkel-like tube at

518-651: A group that included one of the largest insects that ever lived, Meganeuropsis permiana from the Early Permian , with a wingspan around 750 mm (30 in). The Protanisoptera , another ancestral group that lacks certain wing-vein characters found in modern Odonata, lived in the Permian . Anisoptera first appeared during the Toarcian age of the Early Jurassic , and the crown group developed in

592-501: A huge, extensible labium , armed with hooks and spines, which is used for catching prey. This labium is folded under the body at rest and struck out at great speed by hydraulic pressure created by the abdominal muscles. Both damselfly and dragonfly nymphs ventilate the rectum, but just some damselfly nymphs have a rectal epithelium that is rich in trachea , relying mostly on three feathery external gills as their major source of respiration. Only dragonfly nymphs have internal gills, called

666-406: A hybrid flight time (hovering and fixed-wing gliding) of ~25–30 minutes. However, these specifications were announced at the beginning of the crowdfunding campaign and do not reflect any actual hardware. TechJect told investors that The Dragonfly would have the ability to be equipped with up to twenty environmental sensors (including GPS and cameras), dependent on electronics package. At minimum,

740-567: 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

814-408: A later one. In any one area, individuals of a particular "spring species" emerge within a few days of each other. The springtime darner ( Basiaeschna janata ), for example, is suddenly very common in the spring, but disappears a few weeks later and is not seen again until the following year. By contrast, a "summer species" emerges over a period of weeks or months, later in the year. They may be seen on

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888-470: A lens focusing light from one direction on the rhabdom , while light from other directions is absorbed by the dark wall of the ommatidium . The mantis shrimp is the most advanced example of an animal with this type of eye. In the other kind of apposition eye, found in the Strepsiptera , each lens forms an image, and the images are combined in the brain. This is called the schizochroal compound eye or

962-522: 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 (Libellulidae), however, many genera have areas of colour 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

1036-428: A packet of sperm from his primary genital opening on segment 9, near the end of his abdomen, to his secondary genitalia on segments 2–3, near the base of his abdomen. The male then grasps the female by the head with the claspers at the end of his abdomen; the structure of the claspers varies between species, and may help to prevent interspecific mating. The pair flies in tandem with the male in front, typically perching on

1110-494: A rigid, box-like structure with internal bracing, and provide a robust attachment for the powerful wing muscles inside. 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

1184-416: A series of nymphal stages from which the adult emerges. Eggs laid inside plant tissues are usually shaped like grains of rice, while other eggs are the size of a pinhead, ellipsoidal, or nearly spherical. A clutch may have as many as 1500 eggs, and they take about a week to hatch into aquatic nymphs or naiads which moult between six and 15 times (depending on species) as they grow. Most of a dragonfly's life

1258-475: A suitable substrate, but also the male hovering above her or continuing to clasp her and flying in tandem. This behaviour following the transfer of sperm is termed as mate guarding and the guarding male attempts to increase the probability of his sperm fertilising eggs. Sexual selection with sperm competition occurs within the spermatheca of the female and sperm can remain viable for at least 12 days in some species. Females can fertilise their eggs using sperm from

1332-427: A sunlit stretch of shallow water, a special plant species, or the preferred substrate for egg-laying. The territory may be small or large, depending on its quality, the time of day, and the number of competitors, and may be held for a few minutes or several hours. Dragonflies including Tramea lacerata (black saddlebags) may notice landmarks that assist in defining the boundaries of the territory. Landmarks may reduce

1406-589: A territory against others of their own species, some against other species of dragonfly and a few against insects in unrelated groups. A particular perch may give a dragonfly a good view over an insect-rich feeding ground; males of many species such as the Pachydiplax longipennis (blue dasher) jostle other dragonflies to maintain the right to alight there. Defending a breeding territory is common among male dragonflies, especially in species that congregate around ponds. The territory contains desirable features such as

1480-438: 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. Three terminal appendages are on segment 10; a pair of superiors (claspers) and an inferior. The second and third segments are enlarged, and in males,

1554-454: A transparent gap but use corner mirrors instead of lenses. Good fliers like flies or honey bees, or prey-catching insects like praying mantises or dragonflies , have specialized zones of ommatidia organized into a fovea area which gives acute vision. In the acute zone the eye is flattened and the facets larger. The flattening allows more ommatidia to receive light from a spot and therefore higher resolution. There are some exceptions from

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1628-538: A true clade ]   Libellulidae (skimmers) About 3,012 species of dragonflies were known in 2010; these are classified into 348 genera in 11 families . The distribution of diversity within the biogeographical regions are summarized below (the world numbers are not ordinary totals, as overlaps in species occur). Dragonflies live on every continent except Antarctica. In contrast to the damselflies (Zygoptera), which tend to have restricted distributions, some genera and species are spread across continents. For example,

1702-460: A twig or plant stem. The female then curls her abdomen downwards and forwards under her body to pick up the sperm from the male's secondary genitalia, while the male uses his "tail" claspers to grip the female behind the head: this distinctive posture is called the "heart" or "wheel"; the pair may also be described as being "in cop". Egg-laying (ovipositing) involves not only the female darting over floating or waterside vegetation to deposit eggs on

1776-408: A way that resembles a true compound eye. Asymmetries in compound eyes may be associated with asymmetries in behaviour. For example, Temnothorax albipennis ant scouts show behavioural lateralization when exploring unknown nest sites, showing a population-level bias to prefer left turns. One possible reason for this is that its environment is partly maze-like and consistently turning in one direction

1850-491: Is a good way to search and exit mazes without getting lost. This turning bias is correlated with slight asymmetries in the ants' compound eyes (differential ommatidia count). The body of Ophiomastix wendtii , a type of brittle star , was previously thought to be covered with ommatidia, turning its whole skin into a compound eye, but this has since been found to be erroneous; the system does not rely on lenses or image formation. "Dragonfly eyes" (Chinese: 蜻蜓眼 qingting yan ]

1924-475: Is a single large facet that is three times in diameter the others in the eye and behind this is an enlarged crystalline cone. This projects an upright image on a specialized retina. The resulting eye is a mixture of a simple eye within a compound eye. Another version is the pseudofaceted eye, as seen in Scutigera . This type of eye consists of a cluster of numerous ocelli on each side of the head, organized in

1998-452: Is also conflict between the males and females. Females may sometimes be harassed by males to the extent that it affects their normal activities including foraging and in some dimorphic species females have evolved multiple forms with some forms appearing deceptively like males. In some species females have evolved behavioural responses such as feigning death to escape the attention of males. Similarly, selection of habitat by adult dragonflies

2072-478: 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 18 and 45 °C (64 and 113 °F); these insects were able to survive body temperatures above

2146-416: Is not random, and terrestrial habitat patches may be held for up to 3 months. A species tightly linked to its birth site utilises a foraging area that is several orders of magnitude larger than the birth site. Mating in dragonflies is a complex, precisely choreographed process. First, the male has to attract a female to his territory, continually driving off rival males. When he is ready to mate, he transfers

2220-456: Is spent as a nymph, beneath the water's surface. The nymph extends its hinged labium (a toothed mouthpart similar to a lower mandible, which is sometimes termed as a "mask" as it is normally folded and held before the face) that can extend forward and retract rapidly to capture prey such as mosquito larvae, tadpoles , and small fish. They breathe through gills in their rectum , and can rapidly propel themselves by suddenly expelling water through

2294-411: Is the rate at which the ommatidia are turned on and off– this facilitates faster reaction to movement; honey bees respond in 0.01s compared with 0.05s for humans. Compound eyes are typically classified as either apposition eyes, which form multiple inverted images, or superposition eyes, which form a single erect image. Apposition eyes can be divided into two groups. The typical apposition eye has

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2368-568: The Early Jurassic . Dragonflies are represented in human culture on artefacts such as pottery, rock paintings, statues, and Art Nouveau jewellery. 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 colours and agile flight are admired in

2442-530: The Middle Jurassic . They retain some traits of their distant predecessors, and are in a group known as the Palaeoptera , meaning 'ancient-winged'. Like the gigantic griffinflies, dragonflies lack the ability to fold their wings up against their bodies in the way modern insects do, although some evolved their own different way to do so. The forerunners of modern Odonata are included in a clade called

2516-645: The order Odonata . About 3,000 extant species of dragonflies are known. Most are tropical , with fewer species in temperate regions . Loss of wetland habitat threatens dragonfly populations around the world. Adult dragonflies are characterised by a pair of large, multifaceted, compound eyes , two pairs of strong, transparent wings , sometimes with coloured patches, and an elongated body. 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. Dragonflies can be mistaken for

2590-426: The polarization of light. Because a compound eye is made up of a collection of ommatidia, each with its own lens, light will enter each ommatidium instead of using a single entrance point. The individual light receptors behind each lens are then turned on and off due to a series of changes in the light intensity during movement or when an object is moving, creating a flicker-effect known as the flicker frequency, which

2664-555: 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 nymphs that can resist drought and are stimulated to grow rapidly in warm, shallow pools, also often benefiting from

2738-472: The IndieGoGo campaign, TechJect released an update to backers stating that the company "in no position to complete the Dragonfly project in our current condition without a helping hand (partners, additional funding or community support)." TechJect has claimed that the project's failure was the result of a delay in the release of funding by PayPal and IndieGoGo. However, the design was much less mature than what

2812-1055: The Panodonata, which include the basal Zygoptera (damselflies) and the Anisoptera (true dragonflies). Today, some 3,000 species are extant around the world. The relationships of anisopteran families are not fully resolved as of 2021, but all the families are monophyletic except the Corduliidae , and the Austropetaliidae are sister to the Aeshnoidea :   Austropetaliidae   Aeshnoidea (hawkers)   Petaluridae (petaltails)   Gomphidae (clubtails)   Neopetaliidae   Cordulegastridae (goldenrings)   Chlorogomphidae   Synthemistidae (tigertails)   many Synthemistidae genera, incertae sedis   Macromiidae (cruisers)  " Corduliidae " (emeralds) [ not

2886-501: 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

2960-478: The anus. Some naiads, such as the later stages of Antipodophlebia asthenes , hunt on land. The nymph stage of dragonflies lasts up to five years in large species, and between two months and three years in smaller species. When the naiad is ready to metamorphose into an adult, it stops feeding and makes its way to the surface, generally at night. It remains stationary with its head out of the water, while its respiration system adapts to breathing air, then climbs up

3034-458: 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 flattened dorsally into a shield-like disc, which has two transverse ridges. The mesothorax and metathorax are fused into

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3108-646: 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

3182-602: The closely related damselflies , which make up the other odonatan infraorder ( Zygoptera ) and are similar in body plan , 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. Dragonflies make use of motion camouflage when attacking prey or rivals. Dragonflies are predatory insects , both in their aquatic nymphal stage (also known as "naiads") and as adults. In some species,

3256-429: The costs of territory establishment, or might serve as a spatial reference. Some dragonflies signal ownership with striking colours on the face, abdomen, legs, or wings. The Plathemis lydia (common whitetail) dashes towards an intruder holding its white abdomen aloft like a flag. Other dragonflies engage in aerial dogfights or high-speed chases. A female must mate with the territory holder before laying her eggs. There

3330-426: 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, and obtain their typical colours 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

3404-424: The eggs singly in each puncture they make. Dragonfly nymphs vary in form with species, and are loosely classed into claspers, sprawlers, hiders, and burrowers. The first instar is known as a prolarva, a relatively inactive stage from which it quickly moults into the more active nymphal form. The general body plan is similar to that of an adult, but the nymph lacks wings and reproductive organs. The lower jaw has

3478-491: The end of the abdomen enabling them to draw in clean water while they are buried in mud. Naiads can forcefully expel a jet of water to propel themselves with great rapidity. Many adult dragonflies have brilliant iridescent or metallic colours produced by structural colouration , making them conspicuous in flight. Their overall coloration is often a combination of yellow, red, brown, and black pigments, with structural colours. Blues are typically created by microstructures in

3552-429: 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 flaps shed the eggs in water, mostly in flight. Dragonflies having ovipositors use them to puncture soft tissues of plants and place

3626-454: The female lays eggs by tapping the surface of the water repeatedly with her abdomen, by shaking the eggs out of her abdomen as she flies along, or by placing the eggs on vegetation. In a few species, the eggs are laid on emergent plants above the water, and development is delayed until these have withered and become immersed. Dragonflies are hemimetabolous insects; they do not have a pupal stage and undergo an incomplete metamorphosis with

3700-418: 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. Compound eye A compound eye is a visual organ found in arthropods such as insects and crustaceans . It may consist of thousands of ommatidia , which are tiny independent photoreception units that consist of

3774-521: 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

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3848-446: The gills of gravid freshwater mussels. Adults capture insect prey in the air, making use of their acute vision and highly controlled flight. The mating system of dragonflies is complex, and they are among the few insect groups that have a system of indirect sperm transfer along with sperm storage, delayed fertilisation, and sperm competition. Adult males vigorously defend territories near water; these areas provide suitable habitat for

3922-579: 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

3996-601: 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. Fossils of very large dragonfly-like insects, sometimes called griffinflies , are found from 325 million years ago (Mya) in Upper Carboniferous rocks; these had wingspans up to about 750 mm (30 in), though they were only distant relatives, not true dragonflies which first appeared during

4070-428: The male may help to pull her out of the water. Egg-laying takes two different forms depending on the species. The female in some families (Aeshnidae, Petaluridae) has a sharp-edged ovipositor with which she slits open a stem or leaf of a plant on or near the water, so she can push her eggs inside. In other families such as clubtails (Gomphidae), cruisers (Macromiidae), emeralds (Corduliidae), and skimmers (Libellulidae),

4144-439: The most northerly of all dragonflies. 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,

4218-401: The neural superposition eye (which, despite its name, is a form of the apposition eye). The superposition eye is divided into three subtypes; the refracting , the reflecting , and the parabolic superposition eye. The refracting superposition eye has a gap between the lens and the rhabdom, and no side wall. Each lens takes light at an angle to its axis and reflects it to the same angle on

4292-482: The nymphal stage lasts up to five years, and the adult stage may be as long as 10 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 capable of highly accurate aerial ambush, sometimes migrating across oceans, and often live near water. They have a uniquely complex mode of reproduction involving indirect insemination, delayed fertilisation, and sperm competition . During mating,

4366-403: The nymphs to develop, and for females to lay their eggs. Swarms of feeding adults aggregate to prey on swarming prey such as emerging flying ants or termites. 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,

4440-494: The other side. The result is an image at half the radius of the eye, which is where the tips of the rhabdoms are. This kind is used mostly by nocturnal insects. In the parabolic superposition eye , seen in arthropods such as mayflies , the parabolic surfaces of the inside of each facet focus light from a reflector to a sensor array . Long-bodied decapod crustaceans such as shrimp , prawns , crayfish and lobsters are alone in having reflecting superposition eyes , which also have

4514-475: The poetry of Lord Tennyson and the prose of H. E. Bates . The infraorder Anisoptera comes from Greek ἄνισος anisos "unequal" and πτερόν pteron "wing" because dragonflies' hindwings are broader than their forewings . Dragonflies and their relatives are similar in structure to an ancient group, the Meganisoptera or griffinflies, from the 325  Mya Upper Carboniferous of Europe,

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4588-621: The research done at Georgia Institute of Technology 's Intelligent Control Systems Laboratory. That research resulted in Patent 9,290,268, filed in 2011 and granted in March 2016. The TectJect company, which spun off from the Georgia Tech Research Corporation, was to develop this technology into a reliable consumer product. After several major design changes and deviations from the original patent, no reliable solution

4662-411: The spermatheca at any time. Males use their penis and associated genital structures to compress or scrape out sperm from previous matings; this activity takes up much of the time that a copulating pair remains in the heart posture. Flying in tandem has the advantage that less effort is needed by the female for flight and more can be expended on egg-laying, and when the female submerges to deposit eggs,

4736-476: 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 3700 m, represented by a species of Aeshna in the Pamirs . Dragonflies become scarce at higher latitudes. They are not native to Iceland , but individuals are occasionally swept in by strong winds, including

4810-405: The types mentioned above. Some insects have a so-called single lens compound eye, a transitional type which is something between a superposition type of the multi-lens compound eye and the single lens eye found in animals with simple eyes. Then there is the mysid shrimp, Dioptromysis paucispinosa . The shrimp has an eye of the refracting superposition type, in the rear behind this in each eye there

4884-403: The underside of the second segment has a cleft, forming the secondary genitalia consisting of the 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

4958-421: The unit was to be equipped with a 3-axis accelerometer and a 3-axis gyroscope as is required for controlled flight through inertial guidance . At most, the unit was envisioned to equip approximately 20 sensors, including 3-axis accelerometers, 3-axis gyroscopes, 3-axis magnetometers , an ambient light sensor, an ambient humidity sensor, and a differential/absolute pressure sensor. On the third anniversary of

5032-561: 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 eutrophic , not too acidic; 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. Many dragonflies, particularly males, are territorial . Some defend

5106-575: The wetlands to lay their eggs or to find mating partners. Unwanted mating is energetically costly for females because it affects the amount of time that they are able to spend foraging. 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. The wings are powered directly , unlike most families of insects, with

5180-492: The wing bases. Some aeshnids such as the brown hawker ( Aeshna grandis ) have translucent, pale yellow wings. Dragonfly nymphs are usually a well- camouflaged blend of dull brown, green, and grey. Dragonflies and damselflies are predatory both in the aquatic nymphal and adult stages. Nymphs feed on a range of freshwater invertebrates and larger ones can prey on tadpoles and small fish . Naiads of one species, Phanogomphus militaris , may even act as parasites, feeding on

5254-656: The wing for several months, but this may represent a whole series of individuals, with new adults hatching out as earlier ones complete their lifespans. The sex ratio of male to female dragonflies varies both temporally and spatially. Adult dragonflies have a high male-biased ratio at breeding habitats. The male-bias ratio has contributed partially to the females using different habitats to avoid male harassment. As seen in Hine's emerald dragonfly ( Somatochlora hineana ), male populations use wetland habitats, while females use dry meadows and marginal breeding habitats, only migrating to

5328-540: Was found. In their crowdfunding pitches TechJect made a number of dubious claims. The Dragonfly was to be equipped with one of three different electronics packages. These could include the Marc-Basic, Marc-2, and Marc-3. In addition, all models were planned to be built to have camera capability, including stereoscopic vision through dual cameras (available with the Marc-3). HD vision was planned to be optional. Power

5402-460: Was planned to be provided from a single-cell Li-Po battery rated at 250mAh. The actuator system for the wings was going to be based on either magnetic solenoidal actuators (Alpha model - retired for now) or a Continuously Variable Transmission (CVT) for the Delta, Gamma, and Omega models. With a final goal weight of ~25g and a length of 6", the micro UAV was expected to hover for ~8–10 minutes, with

5476-416: Was stated during the crowdfunding campaign, and significant time and money was spent finalizing the mechanical design and selecting appropriate materials. The team apologized to backers for what it termed "our dismal approach to the finish line". Crowdfund Insider has described the state of the project as "road kill" and "dead in the water". TechCrunch espoused the view that TechJect's pitch "always seemed

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