Antlion

Antlions are the larvae of insects in the family Myrmeleontidae, an order (Neuroptera) entirely separate from ants. Antlion larvae are perhaps the most famous engineers among insect predators. The larva digs a conical pit in dry, fine-grained sand by walking backward in a spiral while flicking sand outward with its head. The pit's angle is precisely at the sand's 'angle of repose' — the steepest slope where the sand is just barely stable. Any small insect (typically an ant) that wanders over the rim slides down toward the bottom. The antlion lurks buried at the pit's apex with only its sickle-shaped jaws exposed; it grabs the prey, injects digestive enzymes, and sucks out the contents. If the prey tries to climb out, the antlion flicks sand from below to dislodge it. The larva spends 1-3 years in this configuration, growing through three larval stages before pupating in a silk cocoon spun in the sand. Adults emerge looking like delicate, slow-flying dragonflies — long body, four lacy wings — and have nothing functionally in common with the predatory larvae. Adults live a few weeks, mate, lay eggs in dry sand, and die.