Snakefly

(Snakeflies)

Class: Insecta

Order: Raphidioptera

Number of families: 2

Evolution and systematics

An enormous abundance and diversity of raphidiopteran fossils occur in Jurassic and Cretaceous deposits, within the Mesozoic era. The extraterrestrial impact that occurred 65 million years ago probably led to the extinction of most snake-flies. Raphidioptera from the Tertiary belong to the two extant (non-extinct) families. They represent living fossils. Raphidioptera are currently considered the sister group of Megaloptera and Neuroptera, and all three orders constitute the superorder Neuropterida at the base of the Holometabola— the group of orders containing species that undergo complete metamorphosis. The order Raphidioptera comprises two homogeneous families: Raphidiidae, with 185 species, and Inocelliidae, with 21 described species. The estimated number of extant species may be around 250.

Physical characteristics

Raphidioptera have narrow bodies with an elongate pronotum, movable head, and two pairs of subequal wings whose forewings range from 0.20 to 0.79 in (5 to 20 mm). The head is prognathous, flattened dorsoventrally, with chewing mouthparts, large compound eyes, and in the Raphidiidae, with three dorsal ocelli. The wing venation is net-like, and the hyaline wing membrane contrasts with a bright yellow, brown, or bicolored pterostigma. Females have a long ovipositor, and male genitals may be spectacularly shaped. Larvae are terrestrial and elongate, with a flat prognathous head, chewing mouthparts, and 4 to 7 stemmata. The head and prothorax are strongly sclerotized (hardened), while the mesoand metathorax and abdomen are soft-bodied. Preimaginal pupae are extremely mobile and, except for their small wing pads, are similar to adults.

Distribution

Extant Raphidioptera occur throughout the Holarctic region but have not been found in the northern and eastern parts of North America. Their distribution comprises almost all arboreal parts of the Palaearctic region, including fringes of the Oriental region, with the southernmost records (at higher altitudes) in Morocco, northern Algeria, northern Tunisia, Israel, Syria, northern Iraq, northern Iran, northern Pakistan, northern India, Bhutan, Myanmar, northern Thailand, and Taiwan. In the Nearctic region their distribution is restricted to the southwestern and southern parts of North America; the southernmost records are from the Mexican-Guatemalan border. Most species have small distribution areas and are often restricted to a single mountain range.

Habitat

Snakeflies are restricted to bushy arboreal woodland habitats and to latitudes and/or altitudes with a pronounced winter period, and from sea level to more than 9,840 ft (3,000m). Larvae live under the bark of trees or shrubs (many Raphidiidae, all Inocelliidae) or in the top layer of soil (Raphidiidae). Larvae of a few species sometimes also live in rock crevices.

Behavior

Snakeflies are solitary. Premating communication via antennae and movements of abdomen and wings has been observed in several species. Adults are active only during daytime, where they spend much of their time grooming themselves, combing their foretibiae against parts of the ventrally bent head and then pulling their antennae between their tibiae. As they retract their legs, the tibiae and tarsi are pulled through the mouthparts. Cleaning of the mouthparts starts with moving one mandible aside and proceeds with moving the palps and all other parts against each other. Snakeflies are poor flyers with an extremely low vagility and thus have little capacity for dispersal.

Feeding ecology and diet

Larvae of all snakeflies and adults of Raphidiidae are predaceous, feeding on softskinned arthropods. Adults of both families have been observed feeding on pollen.

Reproductive biology

Two positions of copulation have been found: a "wrecking position" (in Raphidiidae), in which the male hangs head first from the female, being carried by her; and a "tandem position" (in Inocelliidae), in which the male crawls under the female, attaching his head in fixed connection to the fifth abdominal sternite of the female. Copulation lasts a few minutes to 1.5 hours in Raphidiidae and up to three hours in Inocelliidae. Oval cigarlike eggs are laid singly or in a batch by the long ovipositor into crevices of bark or under litter. The egg stage lasts from a few days up to three weeks. The larval period lasts at least one year and at most two or three years, although under experimental conditions the period can stretch up to six years. The number of larval instars is generally 10 or 11 but may reach 15 or more. Pupation occurs in spring, and the pupal stage lasts from a few days up to three weeks. In some species pupation takes place in summer or autumn, and the pupal stage lasts several months, up to 10. The extreme mobility of the pupa is a remarkable primitive feature of snakeflies.

Hibernation may occur in the last larval stage, the penultimate larval stage, or the pupa stage, but never in the egg, prepupa, or adult stages. Snakeflies require a low-temperature period (around 32°F [0°C]) to induce pupation or hatching of the imago. Larvae are often parasitized by various species of the families Ichneumonidae (in particular of the genus Nemeritis) and Braconidae.

Conservation status

Almost all species are restricted to limited areas of refugial character, and a high number of species are endemic to certain mountain ranges or islands. Only three species occur throughout northern Asia to northern and central Europe, while a few species in North America, with distribution centers in the Southwest, have succeeded in reaching southern Canada. Although no species are listed by the IUCN, several species with small distributions are seriously endangered by habitat destruction.

Significance to humans

Woodcut illustrations of snakeflies appeared in the seventeenth century, and first species descriptions were published in the eighteenth century. Several species are beneficial to humans as predators of aphids and other soft-bodied pest arthropods, but trials to introduce them into Australia for biological control failed.

Species accounts

Resources

Aspöck, Horst, Ulrike Aspöck, and Hubert Rausch. Die Raphidiopteren der Erde. 2 vols. Krefeld, Germany: Goecke und Evers, 1991.

Tauber, Catherine A. "Order Raphidioptera." In Immature Insects, edited by Frederick W. Stehr. 2 vols. Dubuque, IA: Kendull/Hunt Publishing Company, 1987–1991.

Acker, Thomas S. "Courtship and Mating Behavior in Agulla species (Neuroptera: Raphidiidae)." Annals of the Entomological Society of America 59 (1966): 1–6.

Aspöck, Horst. "The Biology of Raphidioptera: A Review of Present Knowledge." Acta Zoologica Academiae Scientiarum Hungaricae 48 (2002): 35–50. ——. "Distribution and Biogeography of the Order Raphidioptera: Updated Facts and a New Hypothesis." Zoologica Fennica 209 (1998): 33–44.

Kovarik, Peter W., Horace R. Burke, and Charles W. Agnew. "Development and Behavior of a Snakefly, Raphidia bicolor Albarda (Neuroptera: Raphidiidae)." Southwestern Entomologist 16 (1991): 353–364.

IAN: International Association of Neuropterology. Web site:

Oswald, John D. "Bibliography of the Neuropterida." 2003 [May 8, 2003]. .

[Article by: Ulrike Aspöck, PhD; Horst Aspöck, PhD; Hubert Rausch]

The noun has one meaning:

Meaning #1: predatory insect of western North America having a long necklike prothorax

Snakeflies Fossil range: 145–0 Ma PreЄ Є O S D C P T J K Pg N Early Cretaceous - Recent
Female Raphidia notata
Scientific classification
Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Raphidioptera Handlirsch, 1908 Suborder: Raphidiomorpha
Families
Inocelliidae Raphidiidae and see text
Synonyms
Rhaphidioptera (misspelling) Raphidiodea

Snakeflies are a group of insects in the order Raphidioptera, consisting of about 150 species. Together with the Megaloptera they were formerly placed within the Neuroptera, but now these two are generally regarded as separate orders.

Snakeflies are predatory, both as adults and larvae. They can be quite common throughout temperate Europe and Asia, but in North America occur exclusively in the Western United States, namely in the Rocky Mountains and westward, including the southwestern deserts.

Contents 1 Anatomy and life cycle 2 Systematics 3 Footnotes 4 References

Anatomy and life cycle

Adult snakeflies are characterized by having an elongate prothorax but no modification of the forelegs (as in Mantispidae). They have strong and relatively unspecialised mouthparts, and large compound eyes. Some species also have ocelli. The females typically have a long ovipositor, which they use to deposit their eggs into crevices in bark or rotting wood. The wings are similar in size, with a primitive venation pattern, and a thickened costal margin (or "pterostigma").^[1]

The larvae have large heads with projecting mandibles. The head and the first segment of the thorax are sclerotised, but the rest of the body is soft and fleshy. They have three pairs of true legs, but no prolegs. However, they do possess an adhesive organ on the abdomen, with which they can fasten themselves to vertical surfaces.^[1]

The final larval instar creates a cell in which the insect pupates. However, they do not create a cocoon, and the pupa is fully capable of movement, and often leaves its cell for another location before the adult emerges.^[1]

Systematics

The Megaloptera, Neuroptera (in the modern sense) and Raphidioptera are very closely related, and the new name for this group is Neuropterida^[2]. This is either placed at superorder rank, with the Endopterygota - of which they are part - becoming an unranked clade above it, or the Endopterygota are maintained as a superorder, with an unranked Neuropterida being a part of them. Within the endopterygotes, the closest living relatives of the neuropteridan clade are the beetles.

The two extant families of snakeflies are the Raphidiidae and Inocelliidae. In addition, there are a number of extinct forms known only from fossils. Almost all known snakeflies belong to the suborder Raphidiomorpha. The single exception is the prehistoric family Priscaenigmatidae, sometimes placed in a suborder Priscaenigmatomorpha but more likely a basal lineage that does not warrant the establishment of such a redundant monotypic taxon.^[3]

Fossil snakeflies are known from the Early Cretaceous onwards and these are not even the basalmost forms, suggesting their origin lies deep in the Jurassic at least. In fact, the earliest Neuroptera are from the Permian and thus snakefly ancestors probably even predate the Mesozoic also. Fossil Raphidiomorpha taxa are:^[3]

• Genus Nanoraphidia (incertae sedis)
• Family Alloraphidiidae
• Family Baissopteridae
• Family Mesoraphidiidae

Footnotes

1. ^ ^{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. 445-446. ISBN 0-19-510033-6. 
2. ^ Also called "Neuropteroidea", though the ending "-oidea" is normally used for superfamilies. See references in Haaramo (2008).
3. ^ ^{a b} See references in Haaramo (2008)

References

Wikimedia Commons has media related to: Raphidiidae

• Aspöck, H. (2002): The biology of Raphidioptera: A review of present knowledge. Acta Zoologica Academiae Scientiarum Hungaricae 48(Supplement 2): 35–50. PDF fulltext
• Carpenter, F.M. (1936): Revision of the Nearctic Raphidiodea (Recent and Fossil). Proceedings of the American Academy of Arts and Sciences 71(2): 89–157.
• Grimaldi, David & Engel, Michael S. (2005): Evolution of the Insects. Cambridge University Press. ISBN 0-521-82149-5
• Haaramo, Mikko (2008): Mikko's Phylogeny Archive: Neuropterida. Version of 2008-MAR-11. Retrieved 2008-MAY-05.
• Maddison, David R. (1995): Tree of Life Web Project - Raphidioptera. Snakeflies.

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