Antlions
Palpares caffer
Inverterbrate
| At a Glance | |
| Size | 1.2cm in the larva stage |
| Lifespan | Remarkably long-lived creature - 2-3 years in the larval stage |
| Conservation Status | Least Concern |
Description
Antlion, is a name applied to a group of about 2,000 species of insects in the family Myrmeleontidae. The most well-known genus is Myrmeleon ("antlion"). Strictly speaking, the term "antlion" applies to the larval form of the members of this family.
The antlion larva is a ferocious-appearing creature with a robust plump abdomen tapering towards its end.
The largest forms are found in the predominately African genus Palpares which are found in Krantzkloof NR - these have a wingspan of 16 cm.
The winged form of the adults are sometimes called "antlion lacewings".
Most commonly known by their larva form as a result of the sand-traps that they make to catch their prey.
The length of a fully-grown well-nourished predatory larva is typically up to 1.2 cm, and that of an adult up to 4 cm
Behaviour
In our area the average-sized larva digs a pit about 2 cm deep and 4 cm wide at the edge. Having marked out the chosen site by a circular groove, the antlion larva starts to crawl backwards, 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. As it slowly moves round and round, the pit gradually gets deeper and deeper, until the slope angle reaches the critical angle of repose (that is, the steepest angle the sand can maintain, When the pit is completed, the larva settles down at the bottom, buried in the soil with only the jaws projecting above the surface, often in a wide-opened position on either side of the very tip of the cone.
When an ant or other small insect accidentally steps inside the rim of the pit, it will slip on the soft sand particles on the side of the pit and fall to the bottom. The unfortunate victim usually becomes impaled by the antlion's piercing mandibles. But if it tries to escape, the antlion will flick sand and shower the prey. As this storm of loose sand falls on the slope of the pit, it speeds up the treadmill effect. Eventually the prey tumbles to the bottom toward the waiting antlion.
Diet
The antlion larvae eat small arthropods – mainly ants – while the adults of some species eat small pollen and nectar, while others are predators of small arthropods in the adult stage too.
After the prey has been captured, the antlion drags the victim deeper into the sand where it sucks out its body fluids. The antlion then disposes of the carcass by flicking it out of the pit.
Breeding
The life cycle of the antlion begins with egg-laying. The female antlion repeatedly taps the sand surface with the tip of her abdomen. She then inserts her abdomen into the sand and lays an egg.
The larva makes a globular cocoon of sand stuck together with fine silk spun from a slender spinneret at the posterior end of the body. These cocoons may be buried several centimeters deep in the sand. It remains there for one month, until the completion of the transformation into the sexually mature insect, which then emerges from the case and climbs to the surface. After about 20 minutes the adult's wings are fully opened and it will fly off in search of a mate.
The adult is considerably larger than the larva.
Distribution
Antlions are found through the world and are most common in arid and sandy habitats.
Habitat
Antlions are generally found in most habitats where there is sand.
Threats
None.
Local Information
You will find antlion traps throughout the reserve particularly at the bottom of cliff-faces where the sand is dry and protected by the cliff overhangs.
Interesting Facts
Antlions are absolutely harmless and cause no damage to flowers, people or structures. They are highly beneficial and feed on ants and other insects that fall into their traps. It is best to leave them alone. But, it is interesting for kids (and adults, too) to watch them make their pits and catch their prey. You can speed up the process by dropping an ant or other small insect in their pit.