ANT-LION, the name given to neuropterous insects of the family Myrmeleonidae, with relatively short and apically clubbed antennae and four narrow densely reticulated wings which are usually marked with brown or black. The perfect insects are mostly nocturnal and are believed to be carnivorous. The best-known species, Myrmeleon formicarius, which may be found adult in the late summer, occurs in many European countries, though like the rest of this group it does not occur in England. Strictly speaking, however, the term ant-lion applies to the larval form on account of its peculiar and forbidding appearance and its skilful and unique manner of entrapping prey by means of a pitfall. The sandy-grey abdomen is oval and beset with warts and bristles ; the prothorax forms a mobile neck for the large square head, which carries a pair of long and powerful toothed mandibles.
In dry and sandy soil the ant-lion lays its trap. Having marked out the chosen site by a circular groove, it starts to crawl back wards, using its abdomen as a plough to shovel up the soil. By the aid of one front leg it places consecutive heaps of loosened particles upon its head, then with a smart jerk throws each little pile clear of the scene of operations. Proceeding thus it gradually works its way from the circumference towards the centre. When this is reached and the pit completed, the larva settles down at the bottom, buried in the soil with only the jaws projecting above the surface. Since the sides of the pit consist of loose sand they afford an insecure foothold to any small insect that ventures over the edge. Slipping to the bottom the prey is immediately seized by the lurking ant-lion; or if it attempts to scramble again up the treacherous walls of the pit, is - speedily checked in its efforts and brought down by showers of loose sand which are jerked at it from below by the larva. By means of similar head jerks the skins of insects sucked dry of their contents are thrown out of the pit. A full-grown larva digs a pit about 2 in. deep and 3 in. wide at the edge.
The larva makes a globular case of sand stuck together with fine silk spun, it is said, from a slender spinneret at the posterior end of the body. In this it remains until the completion of the transformation into the sexually mature insect, which then emerges from the case, leaving the pupal integument behind. In certain species of Myrmeleonidae, such as Dendroleon pantheor mis, the larva, although resembling that of Myrmeleon struc turally, makes no pitfall, but seizes passing prey from any nook or crevice in which it shelters. In the United States, 58 species are recognized, and the ant-lion is locally known as doodlebug.