Ant-lion

• If the prey tries to escape up the wall of the pit, the larva flicks grains of sand at it with its head to set off small landslides and bring it down.
• The larva has no functional anus: it stores all its waste through the years its development lasts and does not void it until it becomes an adult.
• Its jaws are hollow: it injects digestive enzymes and sucks out the liquefied tissues of the prey, then flings the empty husk out of the pit.
• Its larva builds a trap: a conical funnel in fine sand, dug in an inward spiral, with its walls at the substrate's exact angle of repose, so that any ant stepping on the rim triggers a slide and slips down to the bottom.
• And if the prey tries to escape, the larva flicks sand grains at it with its head to trigger further slides.
• Buried at the apex, it shows only its jaws: hollow and pincer-shaped, they are what it uses to inject enzymes and suck up the prey's liquefied contents.
• The larva has no functional anus. Its gut is closed and accumulates all its waste throughout the larval stage, which can last two or three years; it expels it all at once on emerging as an adult.
• The adult is completely different: it looks like a fragile, clumsily flying dragonfly, lives only a few weeks and is rarely seen.
• The shape of the funnel depends on hunger: the worst-fed larvae build the largest traps.
• The technique has been known since antiquity and is already described in the Physiologus, a bestiary of the 2nd century.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat and environment

Dry sandy ground sheltered from the rain: eaves, caves and pine woods

Size at birth

Egg of about 1 mm across; the larva reaches up to 1.2 cm in the final instar

Sexual maturity

The adult emerges from the cocoon sexually mature and lives only a few weeks. Britannica holds that it does not feed and that the larva has to build up enough reserves to sustain it; other sources describe adults that catch small insects.

Gestation / incubation

The eggs hatch after 3-5 weeks depending on the temperature and moisture of the soil; the larva goes through three instars over 1 to 3 years and pupates inside a spherical silk cocoon coated with grains of sand

Litter / clutch size

The female lays the eggs one by one, inserting her ovipositor into sandy soil after probing the substrate with the tip of her abdomen, and spreads them around the area

Sources consulted: https://es.wikipedia.org/wiki/Myrmeleon_formicarius; Recopilacion de biologia del genero Myrmeleon; Britannica, ficha Antlion; NCBI PMC3066215, aprendizaje en hormigas leon; fichas divulgativas de Myrmeleontidae; fichas de habitat de Myrmeleon formicarius

Best time: Myrmeleon formicarius matures in late summer; it is distributed across North America and Europe but does not reach England. The adults are nocturnal and come to lights; what is almost always seen is not the insect but its pits in fine sand, at the foot of banks, riverbanks and places sheltered from the rain