The larvae spend their life underground; they create 'ant-lion pits', by burrowing backwards into the sand. The larva buries into the bottom of the pit but leaves its jaws sticking out. When unsuspecting insects, woodlice, spiders and millipedes pass by the pit, the ant-lion larva starts to flick sand at them until they fall in, where they are grabbed by the huge jaws (2), sucked dry and then tossed out of the pit (3). Occasionally the larva may emerge in order to chase its prey, whilst showering it with sand (2). The body of the larva is covered with forward-facing bristles that prevent it from becoming dislodged from its pit. These hairs mean that larvae can only move backwards (2).
Larval ant-lions digest their food so well that they do not produce solid waste; they therefore do not need an anus. Larvae exude only liquid waste; the small amount of solid waste that may build up is excreted by newly emerged adults (2). Ant-lion larvae pass through three stages (called instars) and overwinter twice, before spinning a tough silk cocoon, and entering the pupal stage. Adults emerge from the pupa towards the end of July or in the first few days of August (2). After allowing their wings to harden (3) they gather in a tall pine tree, and a number of males attempt to attract a single female. Volatile compounds given off by males have been discovered; these compounds are thought to stimulate these aggregations (3). Mating involves the male hanging below the female, with his tail attached to that of the female (3). After mating, the female flies to the ground, where she lays her eggs in the sand. She has to be particularly wary of ant-lion larvae at this time, which are the main predators of female adults. Males live for up to 20 days, while females last a little longer, with an average life span of 24 days (2).