scorpion fly

1. A mecopterous insect of the family Panorpidae, having in the male of most species a curved genital structure that resembles the sting of a scorpion.
2. Any mecopterous insect; a mecopteran.

(Scorpionflies and hangingflies)

Class: Insecta

Order: Mecoptera

Number of families: 9

Evolution and systematics

Classified within the order Mecoptera are perhaps the most primitive insects with complete metamorphosis. The fossil record of Mecoptera is rich, dating back to the lower Permian, when they were one of the most abundant insect groups. The modern orders Trichoptera, Lepidoptera, Siphonaptera, Strepsiptera, and Diptera are believed to have descended from a mecopteran ancestor. The order today is made up of remnants of this former diversity, containing about 600 species in nine families: Apteropanorpidae (1 genus, 1 species); Bittacidae (16 genera, 172 species); Boreidae (3 genera, 27 species); Choristidae (3 genera; 8 species); Eomeropidae (1 genus, 1 species); Meropeidae (2 genera, 2 species); Nannochoristidae (2 genera, 7 species); Panorpidae (3 genera, 360 species); and Panorpodidae (2 genera, 9 species). Living examples of Mecoptera vary widely in form and biology. Because of this extreme diversity, the status of the order as a single evolutionary unit is under debate, and it eventually may be divided into several new orders.

Physical characteristics

No single feature unifies the order. Fully winged species share wing structure, having four long, membranous wings, with both the front and hind pairs similar in shape and venation (number and shape of veins in an insect's wings). The order name Mecoptera means "long wings." Mecoptera generally have hyaline (clear) wing membranes with dark veins. When a color pattern exists, it is typically a transparent amber coloration or dark brown banding and striping on the wing membranes. Another common feature is the elongation of the mouthparts and lower portions of the head into a rostrum, a useful character for placing short-winged or wingless species within the order. The mandibles are located at the tip of the rostrum.

Many adult body types exist. Males of Panorpidae and Panorpodidae commonly are called scorpionflies. They have enlarged, bulbous genitalia, carried curled above the body, resembling the tail of a scorpion. The hangingflies, family Bittacidae, look like crane flies (order Diptera), in that they have narrow bodies and long, thin legs. Meropeids and eomeropids are cockroach-like, with flattened bodies and tough, densely veined wings. There are three body types of mecopteran larvae: eruciform (caterpillar-like, with false legs on the abdomen), campodeiform (long and cylindrical, lacking false legs), and scarabaeiform (grublike).

Distribution

Mecoptera are distributed worldwide, including the northern polar regions. Some families are very restricted in distribution. The highest species diversity occurs in the Indomalayan biogeographical region, which encompasses Southeast Asia and Indonesia.

Habitat

Mecoptera are found chiefly in cool, moist habitats. Forests with plentiful shade support the greatest diversity of species. Most larvae develop beneath soil or litter. Nannochoristid larvae, however, are completely aquatic. Adults of Boreidae, called snow scorpionflies, are found on rocks, snow, and ice in the vicinity of moss clumps, within which their larvae develop.

Behavior

Adult Mecoptera tend to be rather secretive, inactive insects, most frequently found resting on the surface of leaves in dense shade. Flight in most species is feeble and brief. Predaceous species typically feed during the day, while opportunistic species have flexible foraging schedules. Reproductive activity in most species takes place only at night.

Feeding ecology and diet

Mecopterans are carnivorous, herbivorous, or omnivorous. Hangingflies are adapted to a predaceous lifestyle. Their hind legs are raptorial, with a single large tarsal claw, used to capture small insect prey. Prey is pierced with the rostrum, and fluids are withdrawn. Snow scorpionflies apparently are an entirely herbivorous group, feeding on mosses as adults and larvae. Most panorpid scorpionflies are omnivores, feeding opportunistically on dead or dying insects but also on plant secretions such as pollen, fruit juice, and nectar. Mecopteran larvae are mostly omnivorous, an exception being the aquatic larvae of Nannochoristidae, which are predaceous on the larvae of midges (order Diptera).

Reproductive biology

Males court nearby females with displays of wing and body movements, and many offer females a nuptial meal.

Common nuptial meals are prey items and salivary secretions. Competition among males often is fierce, and males that are competitively unsuccessful may attempt to force copulation. Females have been shown to prefer males that offer nuptial meals, and feeding on the meal stimulates egg laying and increases fecundity. Mating may last for several hours. Development progresses through four larval instars, a prepupal stage and a pupal stage. Larval development can be as rapid as one month. Adult life span is of similar duration.

Conservation status

No species of Mecoptera is listed by the IUCN. A decline of mecopteran populations in North America, Mexico, and Java has been noted and is attributable to human activity.

Significance to humans

Mecoptera are not known to affect humans in any way. The common name scorpionfly implies that they are in some way dangerous, but no species stings or bites.

Species accounts

Resources

Byers, G. W. "Mecoptera." In The Insects of Australia: A Textbook for Students and Research Workers, edited by CSIRO. 2nd edition. 2 vols. Carlton, Australia: Melbourne University Press, 1991. ——. "Order Mecoptera." In An Introduction to the Study of Insects, edited by D. J. Borror, C. A. Triplehorn, and N. F. Johnson. 6th edition. Philadelphia: Saunders College Publishing, 1989.

Byers, G. W., and R. Thornhill. "Biology of the Mecoptera." Annual Review of Entomology 28 (1983): 203–228.

Myer, John R. "Mecoptera." June 13, 2001 [March 12, 2003]. "The Scorpion Flies (Mecoptera)." February 25, 2003 [March 12, 2003]. . "World Checklist of Extant Mecoptera Species." October 31, 1997 [March 12, 2003]. .

[Article by: Jeffrey A. Cole, BS]

A small order of insects called the scorpion flies. Characteristic of the adult insect is the peculiar prolongation of the head into a beak, which bears chewing mouthparts. They are small to medium in size. The insects either have two pairs of large, net-veined wings of equal size, often with dark areas, or have short and aborted wings. The legs are long and slender. In some species, the male abdomen has a terminal enlargement which is held recurved over the back so that he resembles a scorpion, thus the common name. The Mecoptera are found in moist habitats within densely wooded areas. The adults are omnivorous but feed chiefly on small insects. See also Insecta.

The noun has one meaning:

Meaning #1: any of various mecopterous insects of the family Panorpidae of the northern hemisphere having a long beak and long antennae; males have a tail like that of a scorpion except it is not venomous

Mecoptera Fossil range: 299–0 Ma PreЄ Є O S D C P T J K Pg N Permian - Recent
Panorpa communis, male
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Superorder:	Endopterygota
Order:	Mecoptera Hyatt & Arms, 1891
Families
Apteropanorpidae Bittacidae (hangingflies) Boreidae (snow scorpionflies) Choristidae †Dinopanorpidae Eomeropidae Meropeidae (earwigflies) Nannochoristidae Panorpidae (common scorpionflies) Panorpodidae (short-faced scorpionflies)

Mecoptera (from the Greek: meco- = "long", -ptera = "wings") are an order of insects with about 550 species in nine families worldwide. Mecoptera are sometimes called scorpionflies after their largest family, Panorpidae, in which the males have enlarged genitals that look similar to the stinger of a scorpion. The Bittacidae, or hangingflies, are a prominent family of elongate insects known for their elaborate mating rituals, in which females choose mates based on the quality of gift prey offered by various males.

While modern mecoptera are overwhelmingly predators or consumers of dead organisms, early ones might have played an important role before the evolution of other insects in pollinating extinct gymnosperms.^[1][2]

Contents 1 Anatomy and biology 2 Evolution 3 First pollinators 4 Mating 5 References 6 External links

Anatomy and biology

Mecoptera are small to medium insects with slender, elongated, bodies. They have relatively simple mouthparts, with long mandibles and fleshy palps, which resemble those of the more primitive true flies. Like many other insects, they possess compound eyes on the side of the head, and three ocelli on the top. Most Mecoptera feed on vegetation in moist environments; in hotter climates, they may therefore be active only for short periods of the year.^[3]

The wings are narrow in shape, with numerous cross-veins, and somewhat resemble those of primitive insects such as mayflies. A few genera, however, have reduced wings, or have lost them altogether. The abdomen is cylindrical, and typically curves upwards in the male, superficially resembling the tail of a scorpion.

The female lays the eggs in close contact with moisture, and the eggs typically absorb water and increase in size after deposition. In species that live in hot conditions, the eggs may not hatch for several months, the larvae only emerging when the dry season has finished. More typically, however, they hatch after a relatively short period of time.^[3]

The larvae are usually quite caterpillar-like, with short, clawed, true legs, and a number of abdominal prolegs. They have a sclerotised head with compound eyes and mandibulate mouthparts. The tenth abdominal segment bears either a suction disc, or, less commonly, a pair of hooks. They generally eat vegetation or scavenge for dead insects, although some predatory larvae are known.^[3]

The larva crawls into the soil or decaying wood to pupate, and does not spin a cocoon. The pupae are exarate, meaning that the limbs are free of the body, and are able to move their mandibles, but are otherwise entirely non-motile. In drier environments, they may spend several months in diapause, before emerging as adults once the conditions are more suitable.^[3]

Evolution

DNA evidence indicates that fleas, which are traditionally considered a separate order (Order Siphonaptera), are instead highly specialized Mecoptera^[4]. Grouped together with the fleas, Mecoptera would have about 3000 known species.

Mecoptera have special importance in evolution of Insecta. Two of the most important insect orders, Lepidoptera and Diptera, along with Trichoptera, probably evolved from ancestors belonging to, or strictly related to, the Mecoptera. This is apparent from anatomical and biochemical similarities, but, moreover, transitional fossils, such as Permotanyderus and Choristotanyderus, have been discovered that lie between the Mecoptera and Diptera.^[3]

The group was once much more widespread and diverse than at present, having as many as four suborders during the Mesozoic.^[3]

First pollinators

It has been proposed that extinct mecoptera species were important plant pollinators.^[1][2] Early non-angiosperm gymnosperm seed plants during the late Middle Jurassic to mid–Early Cretaceous period have been believed to be mainly wind-pollinated. However examination of fossil mecoptera show that they had siphon feeding apparatus that could fertize early gymnosperms by feeding on their nectar and pollen. The lack of iron enrichment in their fossilized proboscis rules out a use in blood drinking. One question over this suggestion is that so far pollen has not been found associated with these feeding parts which is surprising for the amber-encased insects which should have preserved pollen but "further fossils may provide this information".^[1]

11 species have been identified belonged to three families, Mesopsychidae, Aneuretopsychidae, and Pseudopolycentropodidae for which "the encompassing name Aneuretopsychina is available".^[2] There length ranges from 3 mm in Parapolycentropus burmiticus to 28 mm in Lichnomesopsyche gloriae.^[2] The proboscis could be as long as 10 mm. Pollen transfer has been suggested to occur by body surface transport on mouthpart and head surfaces like that in bee flies and hover flies--however no such associated pollen has been found even though the insects were preserved in amber.^[2] It is thought that they pollinated such plants as Caytoniaceae, Cheirolepidiaceae, Czekanowskiaceae, Pentoxylaceae, and Gnetales as these have ovulate organs that are either poorly suited for wind pollination or have structures that could support long-proboscid fluid feeding.^[2]

Mating

Gullen and Cranston ^[5] offer a startling description of the mating habits of the Bittacidae:

"Food items such as caterpillars, bugs, and flies are offered to be eaten during copulation. The female is first attracted by a pheromone emitted by one or more vesicles or pouches at the end of the male's abdomen. When the female is near, the vesicles are retracted. The female examines the offering while the male searches for her genitalia with his own. If the gift is rejected, the female flies away. If the gift is accepted, the genitalia of the male couples with that of the female, who lowers herself until she is hanging upside down. She consumes the offering during copulation. The male supports the female by holding her legs or the prey. Field observations show that both sexes mate several times per day. Small or unacceptable offerings result in no or a very short copulation time. Duration depends on the size of the gift. It has been observed that prey 3 to 14 mm long will provide 1 to 17 minutes of copulation in Hylobittacus apicalis. Larger H. apicalis give prey the size of houseflies in return for 20 to 29 minutes of copulation. This results in a maximum sperm transfer, increased oviposition, and a refractory period."

Male genital (Panorpa communis)	Panorpa meridionalis, from Portugal	Bittacidae species from Australia	Panorpa communis female with prey
Panorpa communis male	Detail of head, male (Panorpa communis)	Dinokanaga andersoni Forewing	Male Panorpa communis

References

1. ^ ^{a b c} Ollerton J. Coulthard E. (2009). Evolution of Animal Pollination. Science, 326: 808-809. doi:10.1126/science.1181154
2. ^ ^{a b c d e f} Ren D, Labandeira CC, Santiago-Blay JA, Rasnitsyn A, Shih CK, Bashkuev A, Logan MA, Hotton CL, Dilcher D. (2009). Probable Pollination Mode Before Angiosperms: Eurasian, Long-Proboscid Scorpionflies. Science, 326 (5954), 840-847. doi:10.1126/science.1178338
3. ^ ^{a b c d e f} Hoell, H.V., Doyen, J.T. & Purcell, A.H. (1998). Introduction to Insect Biology and Diversity, 2nd ed.. Oxford University Press. pp. 488-491. ISBN 0-19-510033-6. 
4. ^ Whiting, Michael F. (2002). "Mecoptera is paraphyletic: multiple genes and phylogeny of Mecoptera and Siphonaptera". Zoologica Scripta 31 (1): 93-104. doi:10.1046/j.0300-3256.2001.00095.x. http://www3.interscience.wiley.com/journal/118916123/abstract. 
5. ^ Gullan, P.J. and P.S. Cranston. The Insects: An Outline of Entomology, second edition. 2000: Blackwell Science, Ltd.

• Grimaldi, D. and Engel, M.S. (2005). Evolution of the Insects. Cambridge University Press. ISBN 0-521-82149-5. 
• Archibald, S.B. (2005). "New Dinopanorpida (Insecta: Mecoptera) from the Eocene Okanogan Highlands (British Columbia, Canada and Washington State, USA)". Canadian Journal of Earth Sciences 4 (2): 119–136. doi:10.1139/e04-073. 

External links

Wikispecies has information related to: Mecoptera

• Mecoptera at the Tree of Life
• Mecoptera image gallery at myrmecos.net

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