Megaloprepus caerulatus | |
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female M. caerulatus in Costa Rica | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Odonata |
Suborder: | Zygoptera |
Family: | Coenagrionidae |
Genus: | Megaloprepus Rambur, 1842 |
Species: | M. caerulatus |
Binomial name | |
Megaloprepus caerulatus (Drury, 1782) | |
Megaloprepus caerulatus, also known as the blue-winged helicopter, is a forest giant damselfly of the family Coenagrionidae. Forest giant damselflies were previously recognized as their own family, Pseudostigmatidae. M. caerulatus is found in wet and moist forests in Central and South America. It has the greatest wingspan of any living damselfly or dragonfly, up to 19 centimetres (7.5 in) in the largest males. Its large size and the markings on its wings make it a conspicuous species; a hovering Megaloprepus has been described as a "pulsating blue-and-white beacon". [2]
As an adult it feeds on orb-weaver spiders in the forest understory, which it plucks from their webs. It lays its eggs in water-filled holes in trees; males defend the larger holes as breeding territories. The naiad is a top predator in its tree-hole habitat, feeding on tadpoles and aquatic insects, including the larvae of mosquito species that are vectors of human disease.
Megaloprepus lays its eggs in the water that collects in holes in trees by depositing the eggs within the wet bark. These plant-borne bodies of water, known as phytotelmata, may form in a living tree when a branch breaks off or a burl rots and fills with water, in buttresses of some trees that hold water including the common Pentaclethra macroloba , or indentations in a trunk may fill with water after the tree falls. The eggs hatch in a minimum of 18 days, but the hatching of eggs laid on the same day is spread out over as much as half a year. This extreme variation in hatching time—unknown in any other damselfly but present in some mosquito species—increases the chance that some eggs will hatch when no predator is present. [3]
As with other damselflies, the young—known as naiads, nymphs, or larvae—are carnivorous. The most ubiquitous prey in the tree holes they inhabit are mosquito larvae, but they will also feed on tadpoles, syrphid fly and chironomid fly larvae, and other odonate (dragonfly and damselfly) naiads. [4] The three leaflike caudal lamellae at the end of the abdomen, which serve as gills, are broad and elaborately folded, an adaptation to intermittent low oxygen availability in its habitat. [5] Each lamella has a conspicuous white spot, making Megaloprepus easy to distinguish from other tree-hole damselflies. [6]
As many as 13 females may oviposit in a single large tree hole, laying up to 250 eggs each, but the numbers of naiads are reduced by cannibalism. Even when there is a high concentration of other prey, Megaloprepus naiads still kill each other until a density of one naiad per 1-2 liters of water is reached. [7] They are not territorial, but larger individuals displace smaller ones; their aggressive behavior includes raising and swinging the caudal lamellae and striking with the labium, the hinged, extensible lower "lip" that odonate naiads use to catch prey. [8]
The adult's body is dark brown or black and has yellowish markings. The wings are hyaline (transparent), with a dark blue band on the outer third. Females have a milky-tinged patch at the tip of each wing, while males of most populations have a white band just inside the blue one. [9]
In 1923, Philip Calvert described Megaloprepus in flight: [10]
When flying the four wings are spread quite far apart, fore and hind wing of the same side far apart, body horizontal. Flight slow enough so that the movements of each separate wing can be seen—insect consequently moves slowly but can dodge. Mr. Barnes compared the movements of the wings to that of a windmill, but the revolving movements are lacking; I should say the effect produced by the wings is more like that of a jumping-jack with moveable arms and legs pulled by one string, rather slowly, but, of course, at regular intervals.
It is one of the few species in order Odonata in which males are larger than females, [11] with abdomens up to 10 cm (4 in.) long and wingspans of up to 19 cm (7.5 in.) [12] —the greatest wingspan of all odonates. [13] Size varies geographically; Megaloprepus on Barro Colorado Island in Panama are smaller than those at La Selva Biological Station in Costa Rica or Los Tuxtlas field station in the Mexican state of Veracruz. [14]
Adult lifespans as long as 7 months have been recorded. [15]
Like other pseudostigmatid damselflies, Megaloprepus feeds on web-building spiders. It forages in areas that receive direct sun, such as the gaps created by fallen trees or branches; the light helps it avoid becoming entangled. [16] When it finds a web, it hovers in front of it until it locates the spider. Then it flies backward and quickly darts forward again to grab the spider in its forelegs. Finally it backs away and perches to consume the spider, removing the legs before eating the body. [17]
Most tree holes contain less than a liter of water, but some can hold as much as 50 liters. Male Megaloprepus defend these larger holes as breeding territories, mating with females who come to the tree hole to oviposit. [18]
Several factors make large tree holes more valuable to Megaloprepus than small ones. Not only can their greater volume accommodate more naiads at a time, they have a higher density of prey in the form of tadpoles and mosquito larvae; this allows the naiads to grow more rapidly and reach adulthood sooner. In forests with a dry season, larger tree holes can last nearly a month longer before drying out completely. As a result, large tree holes can produce three cohorts per season, totalling perhaps a few dozen new adults, while only one or two emerge from a small hole. Large tree holes also give Megaloprepus better chances of surviving to emerge if one of its slower-growing relatives in genus Mecistogaster is already present. In a tree hole small enough to be effectively patrolled by a single naiad, the first species to hatch is likely to eat all newcomers, but in a large one Megaloprepus can escape long enough to outgrow and eventually eat an older resident. Finally, probably due to the greater abundance of prey, larger tree holes produce larger males that will be better able to defend a territory themselves when they reach reproductive maturity. [19]
A territorial male drives away other males from his territory by chasing and sometimes hitting them. He does not allow females to lay eggs in the hole he defends without mating with him first, but he does not pursue females who opt instead to leave the scene. The structure of the penis suggests that, as with many other odonates, male Megaloprepus are able to displace sperm from previous matings, ensuring the paternity of the eggs. For their part, females do not choose mates based on size, and will sometimes remate with smaller males who cannot take over a territory and instead adopt a satellite position nearby. At least some females will lay eggs in undefended tree holes before mating again. [20]
Megaloprepus avoids flying across large clearings that lack shaded perches, and has poor flight endurance, achieving a maximum distance of less than 1 km when experimentally released over water. This may limit its dispersal ability, making it particularly vulnerable to habitat fragmentation. While it can breed in secondary forest, it is less common there than in old-growth forest, even when the two are adjacent. Since Megaloprepus reduces the number of adult mosquitoes that emerge from tree holes it inhabits, and some of the species it preys on are important disease vectors, its conservation may have human health implications. [21]
Odonata is an order of predatory flying insects that includes the dragonflies and damselflies. The two groups are distinguished with dragonflies usually being bulkier with large compound eyes together and wings spread up or out at rest, while damselflies are usually more slender with eyes placed apart and wings folded together along body at rest. Adult odonates can land and perch, but rarely walk.
A dragonfly is a flying insect belonging to the infraorder Anisoptera below 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.
Damselflies are flying insects of the suborder Zygoptera in the order Odonata. They are similar to dragonflies but are usually smaller and have slimmer bodies. Most species fold the wings along the body when at rest, unlike dragonflies which hold the wings flat and away from the body. Damselflies have existed since the Late Jurassic, and are found on every continent except Antarctica.
Enallagma cyathigerum is a species found mainly between latitudes 40°N and 72°N; It is widely distributed in the Palearctic, and the Nearctic species Enallagma annexum was at one time considered to be synonymous with it. The species can reach a length of 32 to 35 mm. It is common in many different countries including Russia, Sweden, Norway, Finland, the United States of America, and South Korea. Damselflies are an important link between the health of the aquatic ecosystem and its response to climate change.
The beautiful demoiselle is a species of damselfly belonging to the family Calopterygidae. It is found in Europe, North Africa, and Western Asia. It is often found along fast-flowing waters.
The blue-tailed damselfly or common bluetail is a damselfly, belonging to the family Coenagrionidae.
The Calopterygidae are a family of damselflies, in the suborder Zygoptera. They are commonly known as the broad-winged damselflies, demoiselles, or jewelwings. These rather large damselflies have wingspans of 50–80 mm, are often metallic-coloured, and can be differentiated from other damselflies by the broader connection between the wings and the body, as opposed to the abrupt narrowing seen in other damselfly families. The family contains some 150 species.
The Cordulegastridae are a family of Odonata (dragonflies) from the suborder Anisoptera. They are commonly known as spiketails. Some vernacular names for the species of this family are biddie and flying adder. They have large, brown or black bodies with yellow markings, and narrow unpatterned wings. Their bright eyes touch at a single point, and they can be found along small, clear, woodland streams, flying slowly 30 to 70 cm above the water. When disturbed, however, they can fly very rapidly. They usually hunt high in forest vegetation, and prefer to capture prey resting on leaves or branches.
Sympetrum pedemontanum, the banded darter, is a dragonfly belonging to the genus Sympetrum. It is characterized by its small stature, dark wing bands, and red or yellow body. It lives in areas with low vegetation and stagnant or weakly flowing bodies of water. Although debate exists regarding the taxa's relationship to others in its genus, it can most commonly be identified by its wing bands, bilobed prothorax, and possibly its genitalia.
The Pseudostigmatidae are a family of tropical damselflies, known as helicopter damselflies, giant damselflies, or forest giants. The family includes the largest of all damselfly species. They specialize in preying on web-building spiders, and breed in phytotelmata, the small bodies of water held by plants such as bromeliads.
Megalagrion nesiotes is a species of damselfly in the family Coenagrionidae. Its common name is flying earwig Hawaiian damselfly. In the past, the flying earwig Hawaiian damselfly lived on the islands of Hawaii and Maui, in the U.S. state of Hawaii. Currently, there is only one population left in east Maui. Limited distribution and small population size make this species especially vulnerable to habitat loss and exotic species invasion. The flying earwig Hawaiian damselfly was last found in 2005. Little is known about this species because of the lack of observation. In 2010, the species was federally listed as an endangered species in the United States.
The white-faced darter or small whiteface is a dragonfly belonging to the genus Leucorrhinia in the family Libellulidae, characterised by red and black markings and a distinctive white patch on the head. It is found in wetlands and peat bogs from northern Europe eastwards to Siberia, and the adults are active from around April till September, which is known as the "flight period". It breeds in acidic bodies of water, laying its eggs in clumps of sphagnum moss that provide a safe habitat for larval development. The larvae are particularly vulnerable to predation by fish, and so are usually found in lakes where fish are not present. L. dubia is listed as a species of least concern (LC) by the IUCN Red List, however, it is potentially threatened by habitat destruction, pollution, and climate change.
Sympetrum vicinum, the Yellow-Legged Meadowhawk is one of some fifteen North American species of autumn meadowhawk, which are members of the Odonate family Libellulidae. It grows to 26–35 mm long.
The dot-tailed whiteface is a species of dragonfly in the family Libellulidae. It is also one of the most common and widespread in the genus Leucorrhinia.
Lestes sponsa is a damselfly with a wide Palaearctic distribution. It is known commonly as the emerald damselfly or common spreadwing. Both males and females have a metallic green colour and brown wing spots. It resides near pools with aquatic plants. When resting its wings are usually half opened.
Lestes dryas is a species of damselfly in the family Lestidae, the spreadwings. Its common names include emerald spreadwing, scarce emerald damselfly and robust spreadwing. An alternate name in Ireland is the turlough spreadwing.
The blue corporal, also known as little corporal, is a dragonfly in the Libellulidae, or skimmer family. First described as Libellula deplanata by Jules Pierre Rambur in 1842, it is common across much of the eastern United States.
Odonata are insects with an incomplete metamorphosis (hemimetabolous). The aquatic larva or nymph hatches from an egg, and develops through eight to seventeen instars before leaving the water and emerging as the winged adult or imago.
Procordulia smithii, commonly known as Smith's dragonfly or the ranger dragonfly, is a species of dragonfly that is endemic to New Zealand, as is its close relative Procordulia grayi.
The giant hawker or the gigantic riverhawker, is a species of dragonfly in the family Aeshnidae. It is found throughout Sundaland, having been recorded on Thailand, Peninsular Malaysia, Singapore, Sumatra, and Borneo. It is the type species for the genus Tetracanthagyna.