This family includes the well-known ant lions, named thus because of the habit of larvae feeding mainly on ants and their ferocious appearance and manner of attack. Larvae are also sometimes called "doodlebugs." The genus Myrmeleon is highly specialized, and because of its cosmopolitan distribution and abundance, is the dominant group in the Neuroptera with the possible exception of Chrysopidae. There are ca. 89 species in North America, being most abundant in the South and West. Adults resemble damselflies, with long slender abdomens. However, they differ in being softer-bodied and having rather long clubbed antennae and in possessing a different wing venation. They are feeble fliers that are frequently attracted to lights. The wings are either clear or irregularly spotted.
Reaumur (1742) published an early detailed account of the behavior of Myrmeleon carius L., the accuracy of which was verified by subsequent researchers. Wheeler (1930) provided a review of the biology and behavior of this species. The eggs are small, oval in outline, and are laid during autumn in small groups, adhering end to end, in the sand. Hatching occurs shortly thereafter, and a feeding period occurs before hibernation. The young ant lion is slender, with conspicuous mandibles and a tough integument, which is essential not only for defense but for protection against desiccation. There are several types of setae on the dorsum which serve to transmit the stimuli from falling sand particles to indicate the presence of prey in the pit.
The formation of the pit by the larvae is only during nighttime. First a circular groove is made in the sand, which indicates the pit margin to be formed. The larva moves backward, using its head and closed mandibles to throw the sand from the inner border of the groove to the outside. The circle that is followed in this process is gradually narrowed, thus reducing the cone of sand in the center and deepening the furrow. The pit is finally completed, and the larva takes position at the bottom, with the entire body except the mandibles covered with sand. Here it awaits the coming of prey, which is seized as soon as it tumbles to the pit bottom. If not within reach of the mandibles, it is showered with sand until its struggles bring it nearer. Prey is killed very quickly, and its body juices sucked out. The remains are then removed from the pit by either throwing or dragging.
There are 3 larval instars, not differing appreciably in character, though the body becomes more robust toward maturity. The developmental period is uncertain but may extend over several years. Larvae are capable of existing for very long periods without food. They mature in late spring or early summer, and the spherical double-walled cocoon is then spun beneath the sand. Pupation occurs ca. 1 week later, and the adults emerge in 4-6 weeks. The pupa cuts a circular opening in the cocoon wall with its mandibles and comes to the surface of the sand before casting its skin. In India the behavior of M. contractus Wlk differs from other members of the genus in not forming pits in sand (Gravely & Maulik 1911). Instead the trunks of mango trees which are coated with dried mud are inhabited, and the larvae are usually found on the surface or in shallow depressions. The cocoon is formed in a crevice in the bark, and the adult emerges from the pupal skin, leaving the latter extruded from the opening.