The antlion larva is a ferocious-appearing 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.

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 2-4 centimeters 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.

Antlion pits are very common in sandy washes and riverbeds. They are especially abundant in soft sand beneath trees, such cottonwoods and willows, or under overhanging rocks. In some places they are so numerous that they resemble miniature craters on the surface of the moon. Apparently the larvae prefer dry places that are protected from the rain.

The larvae are relatively easy to catch and maintain in captivity. Although they look ferocious, they pose no serious threat to humans. They are much too small to bite your fingers or drag you into their sand pit. When disturbed, the larva usually remains motionless. It is covered with a layer of dust or sand and is easily overlooked. All you need is a container of soft, dry sand and an ample supply of small, crawling insects for food. We have raised antlion larvae in glass bowls at Wayne's Word and have observed all the intimate details of their entire life cycle. We once had an entire antlion "condominium" in a large plastic tray, that is, until a cat decided to use it for a litter box. Antlions will also be at home in a bowl of sugar or salt, and make their usual circular pits. Sometimes they tend to get a little messy as they flick sugar all over the table top. It is very startling to guests when they reach for a sugar bowl and find a grotesque creature at the bottom flipping grains of sugar at them.

Eventually the larva attains its maximum size and undergoes metamorphosis during which it transforms into a winged adult. The entire length of time from egg to adult may take two or three years. According to Hutchins (Insects, 1966), this unusually long life cycle may be attributed to the uncertainty and irregular nature of its food supply. When it first hatches, the tiny larva specializes in very small insects, but as it grows larger, it constructs larger pits and catches larger prey. When it is full grown, the larva constructs a spherical cocoon of sand grains cemented together with silk. The cocoons of a common species of the southwestern United States are about the same size and shape as large rabbit droppings, and may be buried several centimeters deep in the sand. How the larva accomplishes this under the sand without getting sand grains inside the cocoon is rather remarkable.

When the cocoon is completed, the larva transforms into a pupa where it remains for several weeks (or months). Finally the pupa breaks through the wall of the sand cocoon and pushes itself up to the surface. A beautiful, winged adult antlion crawls out of the pupal case and soon flutters away in search of a mate. Since they are active at night (nocturnal), it is not always that easy to find a mate in the pitch darkness of summer and fall.

Adult antlions are attracted to lights, and their odds of finding a mate may increase on a neon sign or window screen. It is interesting that some insects that are active during the daytime (diurnal), such as butterflies, find their mates by a phenomenon known as "hilltopping." They simply fly upslope to the summit of the nearest hill. In San Diego County, California during the summer months it is common to find dozens of species of butterflies (including beautiful tiger swallowtails) chasing each other in rather erratic flying behavior at the tops of chaparral-covered hills. These remote mountain tops are popular meeting places for sexually active insects looking for mates.

Antlion larvae collected in southern California in September formed their distinctive sand cocoons the following June and July, and winged adults began to emerge in August. During this time they were fed literally hundreds of ants, flies, silverfish and spiders, all collected at the headquarters at Wayne's Word. At times the staff wondered if they would ever stop eating and form their cocoons, especially since we were running out of food for them. Although we had a plentiful supply of Argentine ants (see Wayne's Word Volume 4, Fall 1995), we found that this well-adapted little ant could sometimes escape from the sand pits, only to find food caches in the Wayne's Word kitchen cabinets, often returning with thousands of fellow food foragers.

The use of pitfall traps by primitive cultures dates back many thousands of years in Africa, and yet, antlion larvae have been using this method of capturing prey for millions of years with virtually little or no change. Like other fascinating creatures, their instinctive behavior is genetically programmed, each new generation knowing exactly how to perform seemingly impossible tasks with precision and artistic beauty. Antlions are particularly remarkable with ingenious pitfall traps and their clever method of outmaneuvering prey by creating miniature landslides. Their traps must be effective because antlions are abundant insects and they have been around for millions of years. During its larval life of a year or more, the antlion builds hundreds of pitfall traps and catches hundreds of insects. And yet, when the timing is right, it instinctively knows exactly how to construct a protective cocoon beneath the sand where it will gradually transform into a pupa and ultimately into a winged adult. The sand cocoon, with its glistening crystals of quartz, mica and feldspar, is truly a work of art.

The antlion is just one of many obscure creatures living in the southwestern United States. They are a marvelous little insect to observe in the wild, and they make a fascinating demonstration for a sand terrarium in the classroom. Although they live in a very competitive world, often within disturbed, urbanized areas, they are masters of survival under adverse conditions. If their little crater-like pitfall traps in the sand are obliterated by the wind, rain, animals, or popular two, three or four-wheel vehicles, they just rebuild it and calmly wait for their next prey. In fact, it is this ingenuity and perseverance that undoubtedly explains their survival through countless centuries.

The following information about antlions is summarized from Thomas Eisner's fascinating book For Love of Insects (2003). Ants of the large subfamily Formicinae have a very successful method of defence that involves the discharge of concentrated formic acid. They all possess a formic acid gland, a larger sac in the posterior part of their abdomen. With a concentration exceeding 50 percent, the formic acid is an effective irritant to their predators. When ants are pierced by the sharp jaws of the antlion, they are injected with salivary fluids. The soft insides of the ant are liquified by digestive enzymes and the ensuing "soup" is sucked up by the antlion through its hollow jaws. Studies conducted by Eisner and his colleagues indicate that antlions carefully avoid piercing the contents of the formic acid sac. In addition, the ants only discharge formic acid when they are biting their prey or predator. Ants are unable to bite the antlion's body because of its position beneath the sand. So even though antlions are repelled by formic acid, they avoid this irritant when catching and feeding on ants.

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