Most people know this insect because of the funnel-shaped pit, up to 2 inches in diameter and depth, produced by the larval stages of this insect to trap ants. Larvae have globular abdomens and narrower, flattened heads bearing sickle-shaped jaws. Unlike damselflies, however, ant-lion antennae are prominent and clubbed at the end. Adults appear dragonfly-like but have long clubbed antennae and occasionally are attracted to lights. Larvae are predaceous.
Adults fly infrequently and lay eggs in the sand.
Development may occur over two years. Larvae produce traps by burrowing into the sand backwards and then while going in a circle, they fling up sand to one side using upward jerks of their heads. When complete they remain buried at the bottom of the pit trap with only their jaws exposed. Ants and other small insects falling in the trap are prevented from leaving by the larvae constantly throwing more sand up onto the sides of the trap. Look for larval pit traps in dry sandy areas, such as underneath eaves of houses or overhanging rocks.