Anyone with an interest in their natural surroundings will be well acquainted with the conical holes made by certain species of ‘ant lion’ larvae in areas of soft, sandy soil. The ‘scribble’ lines in the vicinity of these holes are made by the reversing larvae searching for a suitable spot to dig these ‘ant traps’. The little creatures ‘cork-screw’ into the soil, flicking out the sand with their mandibles until they have formed a smooth-sided, cone shaped hole.
Any small walking insect that enters the hole is shot at with grains of sand to keep it sliding towards the bottom of the hole where it is grabbed by the ant lion larva. The prey is often pulled underground to have its juices sucked out through sharp, hypodermic pincers. The winged adults lay eggs on plants and in the soil.
On hatching, the tiny larvae are immediately voracious predators on aphids and other small creatures. They moult a few times before attaining full size. The mouthparts of all the ant lion larvae consist of a pair of long, sharp mandibles serrated on the inner edge. A covered groove runs the length of each ‘jaw’ to form a hypodermic ‘needle’ through which digestive enzymes are injected into the victim and the juices sucked out.
The ant lion larvae are unable to discard waste matter which is stored and disposed of during moulting and pupation. They form a hard, underground cocoon from mucous and sand from which the adult emerges during the first rains. Feet of the adults are sharply clawed for a secure grip and may be used for holding prey in the predatory species.
The bigger species have large eyes which shine brightly in the light of a lamp at night. Children often amuse themselves by encouraging insects into the pits or stirring the hole with a grass stem to evict the occupant larva. Many a macho field guide devoid of ‘big game’ stimulus to keep his clients satisfied has resorted to the diversion of ant lions or dung beetles. I’ve done it myself - but often the full story is not given or understood.
THE ORDER NEUROPTERA
These interesting, flying insects were previously regarded as a single order. They are now regarded as three separate orders :- the RAPHIDIOPTERA (snakeflies) - 80 species in one family in all continents except Australia - and none south of the Sahara in Africa. The MEGALOPTERA (alderflies) - about 300 species in two families - mainly in temperate regions - and the NEUROPTERA (lacewings, mantispids and ant lions) - with about 4,500 species in 16 families - mainly in the tropics. The order is well represented in South Africa by 13 of the 16 known families, with 383 species so far recorded within the region.
The ant lions are classified under three FAMILIES :- The NEMOPTERIDAE contains adults with ribbon-like hind wings some of which are ‘spooned’ at the end with white, brown and black markings. They have long antennae that are not clubbed. The mouthparts of adults are elongated into a ‘beak’ to probe flowers for pollen and nectar. Their larvae, of many of which little is known, are predatory, have long necks and live in dust in areas of low rainfall. About 60 (which is most) of the world’s species occur in Namaqualand and the Karoo.
The ASCALAPHIDAE contains adults with very long antennae with clubbed ends. They generally hold their abdomens at almost right angles to the surface, are often active fliers and predatory with well-developed jaws. The larvae, which can open their pincer-like jaws to 180 degrees, do not construct pits but live under stones, bark or leaves from where they prey on other insects.There are about 50 species known from our region.
The MYRMELEONTIDAE, which is the largest ‘lacewing’ family, contains adults that resemble dragonflies, with similar jaw structure, but with prominent, short, clubbed antennae. The wings are often spotted or blotched with black or brown. This in the family of most interest concerning the larvae that dig pits in which to trap other insects.
Of the 125 species recorded from the region, almost half occur in the western areas of low rainfall. Relatively few species dig pits with most having free-living larvae that hide under objects or roam under deep sand from where they emerge to hunt other insects.
In the eastern lowveld we have a large variety of ant lions. Many of the lighter built species with light spots at the end of the wings will be similar to Macronemurus tinctus (the white-tip grassland antlion) or Palparidius concinnus (the hook-tailed antlion). The larger species, with prominent, dark markings on the wings are most likely to be of the genus Palpares with P. sobrinus (the dotted veld antlion) and P. caffer (the mottled veld antlion) being most common. Be on the lookout for long antennae though, as the blotched long-horned antlion (Tmesibasis lacerata) of the family Ascalaphidae is a similar, large creature with dark blotches on the wings.
The spoon-winged lacewings of the Nemopteridae are also quite commonly seen during the rains. Many of the predatory species prey on aphids and scale insects and the whole of this large order of insects are highly beneficial to agriculture. Many fly at night and are attracted to lights so attempt not to eliminate them in nocturnal spraying operations during the wet season. If they happen to land on you, attracted by light, don’t kill them as they are completely harmless to human beings.