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).

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".

[3] 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.

Antlion adults are easily distinguished from damselflies by their prominent, apically clubbed antennae which are about as long as the head and thorax combined.

[5] 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.

The tip of the abdomen of females shows greater variation than that of males, depending perhaps on oviposition sites, and usually bears tufts of bristles for digging and a finger-like extension.

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 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.

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.

[12] 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.

[7] As ambush predators, catching prey is risky because food arrives unpredictably and, for those species that make traps, maintaining one is costly.

[15] It makes a globular cocoon of sand or other local substrate stuck together with fine silk spun from a slender spinneret at the rear end of the body.

[17] 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.

[18] 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.

Having marked out the chosen site with a circular groove,[22] the antlion larva begins to crawl backward, using its abdomen as a plough to dig up the soil.

[23] 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.

[23] Since the sides of the pit consist of loose sand at its angle of repose,[26] 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.

[27] Recent research has found that antlion larvae often "play dead" for a variable amount of time (from a few minutes up to an hour) when disturbed to hide from predators.

[21] 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.

[33] 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.

"[34] In popular folklore in the southern United States, people recite a poem or chant to make the antlion come out of its hole.

[41] 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 burowing traits with the real antlion larvae.

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.