The antlion larva is a ferocious looking creature with a robust, fusiform body bearing three pairs of walking legs and a slender neck. Its small head bears an enormous pair of sicklelike jaws (mandibles) with several sharp, teethlike projections. Like sharp hypodermic needles, the hollow jaws pierce the victim and suck fluids out of its body. According to R.E. Hutchins (Insects, 1966), the jaws are capable of injecting venom which digests and dissolves the body contents of the prey.
Antlions are members of a large order of unusual insects, the Neuroptera. They are often called the "nerve-winged insects" because of the elaborate pattern of longitudinal and cross-veins (nerves) in the four wings of adults. The order Neuroptera also includes Dobsonflies and Lacewings and is the most primitive order of insects. These insects undergo complete metamorphosis with an egg, larva, pupa and winged adult. The larval stage is typically a grotesque, wingless creature with long, sicklelike jaws. Pupation usually occurs in a silken cocoon; however, the silk is not derived from modified salivary glands as in most insects, but is produced by the Malpighian tubules and is spun from the anus! The order includes many predaceous, night-flying species, including lacewings, alderflies, snakeflies and dobsonflies. The immature or larval stage of dobsonflies, called hellgrammites, are familiar to fishermen and fisherwomen because they are commonly used as bait. One curious member of the order, called a mantispid, shows a striking resemblance to a miniature preying mantis with enlarged, grasping front legs.
In some species, the larva excavates a conical pit in the sand by crawling backwards in circles, at the same time flipping out sand grains with its long jaws. As it moves round and round, the pit gradually gets deeper and deeper. Eventually the crater reaches 2inches across and almost as deep, with very steep walls. The slope of the funnel is adjusted to the critical angle of repose for sand, so that the sides readily give way under the feet of a would-be escapee. The larva waits quietly at the bottom of the pit, with its body off to one side and concealed by the steep wall. Only its sicklelike jaws protrude from the sand and often they are in a wide-opened position.
When crawling insects, such as ants, inadvertently fall into the pit it is virtually impossible for them to climb the loose sand on the steep walls. To make matters worse, the antlion quickly flips out more sand, thus deepening the pit and causing miniature landslides along the walls which knock the struggling ant to the bottom. If the ant or other insect is large enough it may escape, but usually its struggle is hopeless when it is seized by the powerful jaws of the antlion. Antlion larvae are capable of capturing and killing a variety of insects, and can even subdue small spiders. Often the struggling victim is pulled beneath the sand as its body fluids are gradually siphoned out. After consuming all the contents, the lifeless, dry carcass is flicked out of the pit, and the pit is readied for a new victim.