Antlion

The antlions are a group of about 2,000 species of insect in the neuropteran family Myrmeleontidae. They are known for the predatory habits of their larvae, which mostly dig pits to trap passing ants or other prey. In North America, the larvae are sometimes referred to as doodlebugs because of the marks they leave in the sand. The adult insects are less well known due to their relatively short lifespans in comparison with the larvae. Adults, sometimes known as antlion lacewings, mostly fly at dusk or just after dark and may be mistakenly identified as dragonflies or damselflies.

Antlions have a worldwide distribution. The greatest diversity occurs in the tropics, but a few species are found in cold-temperate locations, one such being the European Euroleon nostras. They most commonly occur in dry and sandy habitats where the larvae can easily excavate their pits, but some larvae hide under debris or ambush their prey among leaf litter.

Antlions are poorly represented in the fossil record. Myrmeleontiformia is generally accepted to be a monophyletic group, and within the Myrmeleontoidea, the antlions' closest living relatives are thought to be the owlflies (Ascalaphidae). A 2019 study finds Myrmeleontidae to be monophyletic, aside from Stilbopteryginae and Palparinae, which form separate clades closer to Ascalaphidae. The predatory actions of the larvae have attracted attention throughout history and antlions have been mentioned in literature since classical times.

Etymology

The exact meaning of the name "antlion" is uncertain. It has been thought to refer to ants forming a large percentage of the prey of the insect, the suffix "lion" merely suggesting "destroyer" or "hunter". In any case, the term seems to go back to classical antiquity. The antlion larva is often called a "doodlebug" in North America because of the odd winding, spiralling trails it leaves in the sand while relocating, which look as if someone has been doodling.

The scientific name of the type genus Myrmeleon – and thus, the family as a whole – is presumably derived from Ancient Greek μύρμηξ (múrmex), meaning "ant" λέων (léon), meaning "lion", in a loan translation of the names common across Europe. In most European and Middle Eastern languages, at least the larvae are known under the local term corresponding to "antlion". Also, the pattern of wing venation differs, and compared to damselflies, the adults are very feeble fliers and are normally found fluttering about at night in search of a mate. Adult antlions are typically nocturnal, and rarely seen by day.

The antlion larva has a robust fusiform body, a very plump abdomen, and a thorax bearing three pairs of walking legs. The prothorax forms a slender mobile "neck" for the large, square, flattened head, which bears an enormous pair of sickle-like jaws with several sharp, hollow projections. The jaws are formed by the maxillae and mandibles; the mandibles each contain a deep groove over which the maxilla fits neatly, forming an enclosed canal for injecting venom to immobilise the victim, and enzymes to digest its soft parts. The larva is clad in forward-pointing bristles which help it to anchor itself and exert greater traction, enabling it to subdue prey considerably larger than itself.

Antlion larvae are unusual among insects in lacking an anus. All the metabolic waste generated during the larval stage is stored; some is used to spin the silk for the cocoon and the rest is eventually voided as meconium at the end of its pupal stage.

File:Doodlebug doodles.jpg|Doodlebug (antlion) doodles and pit traps in the Grand Canyon

File:Antlion (Myrmecaelurus trigrammus) Macedonia.jpg|Adult of Myrmecaelurus trigammus

File:Common Antlion Myrmeleon immaculatus mature nymph.jpg|Larva of Myrmeleon immaculatus

File:Antlion mandible with a visible maxilla for injecting venom.jpg|The bottom side of larval mandible with a visible maxilla for injecting venom

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Distribution

There are about 2,000 species of antlion found in most parts of the world, with the greatest diversity being in warmer areas. The best known species are those in which the larvae dig pits to trap their prey, but not all species do this. Antlions live in a range of usually dry habitats including open woodland floors, scrub-clad dunes, hedge bases, river banks, road verges, under raised buildings and in vacant lots.

Life-cycle

thumb|upright=1.5|The life-cycle of [[Distoleon tetragrammicus]]

Apart from pit-trap-forming taxa, the biology of members of the family Myrmeleontidae, to which the antlions belong, has been little studied. The life-cycle begins with oviposition (egg-laying) in a suitable location. The female antlion repeatedly taps the prospective laying site with the tip of her abdomen and then inserts her ovipositor into the substrate and lays an egg.

Depending on the species and where it lives, the larva either conceals itself under leaves, debris or pieces of wood, hides in a crack or digs a funnel-shaped pit in loose material. They can take several years to complete their life-cycle; they mature faster with plentiful food, but can survive for many months without feeding. In cooler climates they dig their way deeper and remain inactive during the winter. The adult typically lives for about 25 days, but some insects survive for as long as 45 days. In certain species of Myrmeleontidae, such as Dendroleon pantherinus, the larva, although resembling that of Myrmeleon structurally, makes no pitfall trap, but hides in detritus in a hole in a tree and seizes passing prey. In Japan, Gatzara jezoensis larvae lurk on the surface of rocks for several years while awaiting prey; during this time they often become coated with lichen, and have been recorded at densities of up to 344 per square metre.

The larva is a voracious predator. Within a few minutes of seizing its prey with its jaws and injecting it with venom and enzymes, it begins to suck out the digestion products.

Pit-building species

Funnel-shaped pits are built by members of just 3 antlion tribes: Myrmeleontini, Myrmecaelurini, and Nesoleontini. the antlion larva begins to crawl backward, using its abdomen as a plough to dig up the soil. Using one of its front legs, it places heaps of loosened particles upon its head which it then flicks clear of the scene of operations. Continuing in this way, it gradually works its way from the circumference toward the center.

When the pit is completed, the larva settles down at the bottom, buried in the soil with only the jaws projecting above the surface, often in a wide-opened position on either side of the very tip of the cone. The steep-sloped trap that guides prey into the larva's mouth while avoiding crater avalanches is one of the simplest and most efficient traps in the animal kingdom. The fine grain lining ensures that the avalanches which carry prey are as large as possible. they afford an insecure foothold to any small insects that inadvertently venture over the edge, such as ants. Slipping to the bottom, the prey is immediately seized by the lurking antlion; if it attempts to scramble up the treacherous walls of the pit, it is speedily checked in its efforts and brought down by showers of loose sand which are thrown at it from below by the larva.

Antlion larvae often "play dead" (from a few minutes up to an hour) when disturbed to put off predators. The method is effective; it increased survival rates in patches that use it by 20%. Furthermore, they appear to have maximized its usefulness—further increasing the duration is not likely to convey substantial survival benefits to the larvae.

File:Antlion trap.jpg|Sand pit trap

File:Antlion larva.jpg|Larva extracted from sand pit

File:Antlion pincers in Martin Frobenius Ledermüller’s Microscopic Delights (1759–63).jpg|Microscopic illustration of an antlion larva's pincer by Martin Frobenius Ledermüller (1759–1763)

File:AmeisenlöwenTrichter.jpg|Sand pit trap with remains of an ant

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Evolution

The closest living relatives of antlions within the Myrmeleontoidea are the owlflies (Ascalaphidae); the Nymphidae are more distantly related. The extinct Araripeneuridae and Babinskaiidae are considered likely to be stem groups in the Myrmeleontiformia clade. The phylogeny of the Neuroptera has been explored using mitochondrial DNA sequences, and while issues remain for the group as a whole (the "Hemerobiiformia" being paraphyletic), the Myrmeleontiformia is generally agreed to be monophyletic, giving the following cladogram:

The subfamilies are shown below; a few genera, mostly fossil, are of uncertain or basal position. The fossil record of antlions is very small by neuropteran standards. However, some Mesozoic fossils attest to the antlions' origin more than 150 million years ago. These were at one time separated as the Palaeoleontidae, but are now usually recognized as early antlions.

Stilbopteryginae Newman, 1853

Stilbopterygini Newman, 1853

Acanthaclisinae Navas, 1912

Acanthaclisini Navas, 1912

Palparinae Banks, 1911

Dimarini Navas, 1914
Palparidiini Markl, 1954
Palparini Banks, 1911
Pseudimarini Markl 1954

Myrmeleontinae Latreille, 1802

Brachynemurini Banks, 1927
Dendroleontini Banks, 1899
Gepini Markl, 1954
Gnopholeontini Stange, 1994
Lemolemini Stange, 1994
Maulini Markl 1954
Myrmecaelurini Esben-Petersen, 1918
Myrmeleontini Latreille, 1802
Nesoleontini Markl, 1954

Machado et al. (2018) classification

A subsequent revision by Machado et.al recognized a different four subfamilies, notable in the inclusion of the family Ascalaphidae as a subfamily instead of as a sister taxon to Myrmeleontidae: Ascalaphinae, Myrmeleontinae, Dendroleontinae, and Nemoleontinae.

Ascalaphinae Rambur, 1842

Ascalaphini Lefèbvre, 1842
Dimarini Navas, 1914
Haplogleniini Newman, 1853
Palparini Banks, 1911
Stilbopterygini Newman, 1853
Ululodini Van der Weele 1909

Myrmeleontinae Latreille, 1802

Acanthaclisini Navas, 1912
Brachynemurini Banks, 1927
Myrmecaelurini Esben-Petersen, 1918
Myrmeleontini Latreille, 1802
Nesoleontini Markl, 1954

Dendroleontinae Banks, 1899

Acanthoplectrini Markl, 1954
Dendroleontini Banks, 1899
Glenurini Banks, 1927
Megistopini Navas, 1912

Nemoleontinae Banks, 1911

Nemoleontini Banks, 1911
Protoplectrini Tillyard, 1916

Jones (2019) classification

Jones dissented with Machado et al. and presented an alternative classification, restoring the Ascalaphidae to its traditional family-rank placement, and elevating Palparinae and Stilbopteryginae to family level, leaving only a single subfamily in Myrmeleontidae sensu stricto. However, this classification has been rejected by Hévin et al. (2023), finding the taxonomic decisions to be "not substantiated, with only the family name Palparidae being mentioned in isolation."

Myrmeleontinae Latreille, 1802

Acanthaclisini Navas, 1912
Brachynemurini Banks, 1927
Dendroleontini Banks, 1899
Myrmecaelurini Esben-Petersen, 1918
Myrmeleontini Latreille, 1802
Nemoleontini Banks, 1911
Nesoleontini Markl, 1954

File:Antlion doodles.jpg|Antlion larva trails (doodles) in sand

File:2015.10-434-146bp antlion(unidentified sp.,adult,L(wing tip-antnena tip)4.8cm) DD11.176086,-4.335053@Bobo-Dioulasso,BF thu29oct2015-1054h.jpg|Thorax and head (with club-shaped antenna) of antlion adult

File:Antlion1 by Jonathan Numer.jpg|Larva

File:Formicaleone.jpg|20x closeup of larva

File:Antlion.ogv|Video of antlion larva trying to catch prey with sand traps and eating a small spider

File:Antlion video.ogv|Video of a larva trapping an ant by throwing sand at it

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In culture and folklore

thumb|upright|[[Myrmecoleon, from the Hortus Sanitatis of Jacob Meydenbach, 1491]]

In popular folklore in the southern United States, people recite a poem or chant to make the antlion come out of its hole. Similar practices have been recorded from Africa, the Caribbean, China and Australia.

The Myrmecoleon was a mythical ant–lion hybrid written about in the 2nd century AD Physiologus, where animal descriptions were paired with Christian morals. The ant-lion as described was said to starve to death because of its dual nature – the lion nature of the father could only eat meat, but the ant half from the mother could only eat grain chaff, thus the offspring could not eat either and would starve. It was paired with the Biblical verse Matthew 5:37. The fictional ant-lion of Physiologus is probably derived from a misreading of Job 4:11.

In Japan, both the insect and its pit-traps are popularly known as . This term has since become a stock colloquialism for any "inescapable" trap, whether literal or metaphorical (e.g. an unpleasant social obligation).

Antlions appear as antagonists in the 1991 life simulation video game, SimAnt, and (in a giant form) in the Final Fantasy series, Grounded, Terraria, Don't Starve Together, Monster Rancher 2, Mother 3 and in the Half-Life 2 video game series as an unrelated alien insect species sharing sand burrowing traits with the real antlion larvae. The Trapinch, Vibrava, and Flygon Pokémon evolution line is based on an antlion. The fictional sarlacc from the Star Wars franchise is often compared to the real-life antlion. It also appears as a predator in the film Enemy Mine.

In the third book of Tove Jansson's Moomins series, Finn Family Moomintroll, a rather large and fanciful antlion appears in the second chapter, depicted as a sand-dwelling predator with the literal head of a lion.

Etymology

Distribution

Life-cycle

Pit-building species

Evolution

Machado et al. (2018) classification

Jones (2019) classification

In culture and folklore

See also

Notes

References

External links