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Temporal range: Permian - Recent 299–0 Ma
Skorpionsfliege Panorpa communis male full.jpg
Panorpa communis, male
Scientific classification e
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
(unranked): Antliophora
Order: Mecoptera
Hyatt & Arms, 1891

Mecoptera (from the Greek: meco- = "long", -ptera = "wings") are an order of insects in the superorder Endopterygota 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.[2][3]

Anatomy and biology[edit]

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 sides of their heads, 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.[4]

Male Panorpa dubia.
A, Body in lateral view; B–D. male genital bulb and gonostyli. B, dorsal view; C, ventral view; D, lateral view. ep, epandrium; gcx, gonocoxite; gs, gonostylus; hv, hypovalva; hyp, hypandrium. Scale bars represent 3 mm in A, 1 mm in B–D

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 tip containing an enlarged structure called the genital bulb.

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. The larvae are usually quite caterpillar-like, with short, clawed, true legs, and a number of abdominal prolegs. They have sclerotised heads 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. The larva crawls into the soil or decaying wood to pupate, and does not spin a cocoon. The pupae are exarate, meaning the limbs are free of the body, and are able to move their mandibles, but are otherwise entirely nonmotile. In drier environments, they may spend several months in diapause, before emerging as adults once the conditions are more suitable.[4]

Evolution and phylogeny[edit]

Mecoptera have special importance in the evolution of the insects. Two of the most important insect orders, Lepidoptera (butterflies and moths) and Diptera (true flies), along with Trichoptera (caddisflies), probably evolved from ancestors belonging to, or strictly related to, the Mecoptera. Evidence includes anatomical and biochemical similarities as well as transitional fossils, such as Permotanyderus and Choristotanyderus, which lie between the Mecoptera and Diptera. The group was once much more widespread and diverse than it is now, with four suborders during the Mesozoic.[4] The Mecoptera and Siphonaptera (fleas) share features such as the production of the rubbery cuticle material resilin and panoistic ovarioles which have germ cells forming a continuous tube in place of the usual nurse cells. The Mecoptera are related to these other insect orders as shown in the cladogram, based on a 2008 analysis of four loci (18S and 28S ribosomal DNA, cytochrome oxidase II, and elongation factor 1-alpha) for 128 flea taxa from around the world. The Boreidae (snow scorpionflies) are seen to be the sister clade to the Siphonaptera, so the Mecoptera as traditionally understood was paraphyletic, though the rest of the order forms a clade.[5][6][7][8][9]

part of Endopterygota


Diptera Common house fly, Musca domestica.jpg

Mecoptera (scorpionflies, hangingflies, 400 spp.) (exc. Boreidae) Gunzesrieder Tal Insekt 3.jpg

Boreidae (snow scorpionflies, 30 spp.) Boreus hiemalis2 detail.jpg

Siphonaptera (fleas, 2500 spp.) Pulex irritans female ZSM.jpg

Trichoptera (caddisflies) Sericostoma.personatum.jpg

Lepidoptera (butterflies and moths) Tyria jacobaeae-lo.jpg

Hymenoptera (sawflies, wasps, ants, bees) AD2009Sep09 Vespula germanica 03.jpg

First pollinators[edit]

Extinct Mecoptera species may have been important pollinators of early gymnosperm seed plants during the late Middle Jurassic to mid–Early Cretaceous period. These were mainly wind-pollinated, but fossil mecopterans had siphon feeding apparatus that could have fertilized these early gymnosperms by feeding on their nectar and pollen. The lack of iron enrichment in their fossilized probosces rules out a use in blood drinking. However, pollen has not been found associated with these feeding parts, which is surprising given the preservation of amber-encased insect fossils.[2][3]

Eleven species have been identified from three families, Mesopsychidae, Aneuretopsychidae, and Pseudopolycentropodidae within the Aneuretopsychina. Their lengths range from 3 mm in Parapolycentropus burmiticus to 28 mm in Lichnomesopsyche gloriae. The proboscis could be as long as 10 mm. Pollen transfer has been suggested to occur by body surface transport on mouthparts and head surfaces like that in bee flies and hover flies, but no such associated pollen has been found, though the insects were preserved in amber. They likely pollinated plants such as Caytoniaceae, Cheirolepidiaceae, and Gnetales, which have ovulate organs that are either poorly suited for wind pollination or have structures that could support long-proboscid fluid feeding.[3]


Scorpionflies in the Bittacidae provide a nuptial meal in the form of a captured insect prey, such as a caterpillar, bug, or fly. The male attracts a female with a pheromone from vesicles on his abdomen; he retracts these once a female is nearby, and presents her with the prey. While she evaluates the gift, he locates her genitalia with his. If she stays to eat the prey, his genitalia attach to hers, and the female lowers herself into an upside-down hanging position, and eats the prey while mating. Larger prey result in longer mating times. In Hylobittacus apicalis, prey between 3 and 14mm long give between 1 and 17 minutes of mating. Larger males of that species give prey as big as houseflies, earning up to 29 minutes of mating, maximal sperm transfer, more oviposition, and a refractory period during which the female does not mate with other males: all of these increase the number of offspring the male is likely to have.[10]

Interaction with humans[edit]

Forensic entomology makes use of scorpionflies' habit of feeding on human corpses. Scorpionflies were the first insects to arrive at a donated human cadaver observed (by the entomologist Natalie Lindgren) at the Southeast Texas Applied Forensic Science Facility near Huntsville, Texas, and remained on the corpse for one and a half days. The presence of scorpionflies thus indicates that a body must be fresh.[11][12]

Scorpionflies are sometimes described as looking "sinister", particularly from the male's raised "tail" resembling a scorpion's sting.[13]



  1. ^ Byers, G. W. and Thornhill, R. 1983. Biology of the Mecoptera. Annual review of Entomology. 28: 203-228
  2. ^ a b Ollerton J.; Coulthard E. (2009). Evolution of Animal Pollination. Science, 326: 808-809. doi:10.1126/science.1181154
  3. ^ a b c Ren D., Labandeira C.C., Santiago-Blay J.A., Rasnitsyn A., Shih C.K., Bashkuev A., Logan M.A., Hotton C.L., Dilcher D. (2009). Probable Pollination Mode Before Angiosperms: Eurasian, Long-Proboscid Scorpionflies. Science, 326 (5954), 840-847. doi:10.1126/science.1178338
  4. ^ a b c 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. 
  5. ^ Whiting, Michael F.; Whiting, Alison S.; Hastriter, Michael W.; Dittmar, Katharina (2008). "A molecular phylogeny of fleas (Insecta: Siphonaptera): origins and host associations". Cladistics. 24: 1–31. doi:10.1111/j.1096-0031.2008.00211.x. 
  6. ^ Yeates, David K.; Wiegmann, Brian. "Endopterygota Insects with complete metamorphosis". Tree of Life. Retrieved 24 May 2016. 
  7. ^ 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. 
  8. ^ Wiegmann, Brian; Yeates, David K. (2012). The Evolutionary Biology of Flies. Columbia University Press. p. 5. ISBN 978-0-231-50170-5. Recently, a close affinity between Siphonaptera and Mecoptera has been convincingly demonstrated via morphology (Bilinski et al. 1998) and molecular data (Whiting 2002), rendering Mecoptera paraphyletic, but making the clade including Mecoptera and Siphonaptera monophyletic... there is a general consensus among entomologists that the relationships described above are relatively well established. 
  9. ^ Bilinski, S. M.; Büning, J.; Mimiczyjew, B. (1998). "The ovaries of Mecoptera: basic similarities and one exception to the rule". Folia Histochem Cytobiol. 36 (4): 189–195. PMID 10051973. 
  10. ^ Gullan, P. J.; Cranston, P. S. (2010). The Insects: An Outline of Entomology (4th ed.). Wiley. p. 129. ISBN 978-1-118-84615-5. 
  11. ^ Rutsch, Poncie (22 January 2015). "Finding Crime Clues In What Insects Had For Dinner". NPR. Retrieved 22 June 2015. 
  12. ^ "Southeast Texas Applied Forensic Science Facility". STAFS. 
  13. ^ "Weirdest Looking Bugs". EnkiVillage. Retrieved 22 June 2015. 


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