Ant Lions and Doodlebugs

Have you ever been walking along on some sandy soil, perhaps a path through the woods, a vacant lot, or some bare area under a tree, and looked down to see numerous little round pits in the sand? These little depressions could range from one to three inches in diameter, and dozens of them could be present in just a few square feet – depending on how good the pickings are in that location. As a curious child I would stop to investigate, and with a small twig or piece of dry grass stem I would poke around at the bottom of that pit. Much to my surprise, now and then something would fling a little bit of sand back at me, so now I absolutely HAD to see what was down there. You have to be quick now, for once it is disturbed the resident insect in that pit will quickly go deeper, but with luck you might be able to dig out a little “doodlebug”, the larva of an insect called an Antlion.

The name ant lion is derived from the habit of the doodlebug larva to prey on ants and other small insects that may stumble into its pit. The sandy soils they choose for their pits are perfect traps for crawling insects like ants, which have difficulty climbing back out once they have tumbled in. As they try to climb back up the steep walls the sand continues to slide under their feet, and they continually end up back at the bottom. The doodlebug itself has a hand in this, for it quickly detects the presence of the ant in its pit by the bits of sand falling to the bottom. Immediately the doodlebug begins flinging sand by using its massive jaws (mandibles), and this bombardment adds to the difficulty the ant has in removing itself from this trap. Once the ant tumbles to the very bottom of the pit the doodlebug clamps its jaws around the ant and drags it under, where it then is consumed. Ant “lion” is a very descriptive name.

Its other more colorful name of “doodlebug” is also appropriate, and it refers to the squiggly patterns these insects make on the top of that sand as they move from place to place. Their huge mandibles make walking while facing forward nearly impossible, so they walk backwards, dragging their mandibles behind them. Walking in a straight line seems to be difficult for them, so they end up moving in various directions, leaving behind the meandering line which reminds us of our “doodling” on a piece of paper, perhaps as we sit through a long phone conversation.

Despite its fearsome appearance in these images, we have to recognize that this is a very small insect, and it is not capable of harming people. The jaws are strong enough to capture a tiny ant, but far too small and weak to pinch our skin. The adult antlion feeds on a variety of foods, such as nectar, pollen, or even other small insects, depending on the species of antlion. The adult is often mistaken for more familiar insects such as damselflies or caddisflies. It has two pairs of very long wings, a long, thin body, and relatively short antennae. But, unlike damselflies the antlion adult is a very weak flier, moving about in a fluttering motion. They may often be attracted to lights at night, and you will see them resting on the wall of your front porch. Most species are only about 1 to 2 inches long in the adult stage, but in the southwest, such as in Arizona, there is a giant species called, appropriately, the Giant Ant Lion – Vella fallax – which has wings that may be more than 3 inches long, giving it a wingspan of over 7 inches.

Antlions are in the insect family Myrmeliontidae, with a variety of different species, some with habits very different from the typical sand-pit kinds. There is one species found in the southern states whose larva inhabits tree holes of the burrows of turtles. Other kinds may just hide out in any available crevice, and lunge out to snatch other insects that happen to walk past its hiding place. But, it is those antlion larvae that create the pits in the sand that attract our attention, and the doodlebug is perfectly built for this activity. It begins by marking out just where its pit is going to be, and then begins to dig from the outside of that circle. It piles bits of sand onto its head and then flings this sand outward with a quick movement. The “neck” behind the head is very narrow, giving it the flexibility needed for this movement. It continues to move around the perimeter of its pit until the walls of the pit are as steep as they can be without sand sliding down, and now the doodlebug buries itself at the very bottom, often with its jaws sticking out of the sand and at the ready for the first victim to fall into the pit.

The antlion larva has a little help in capturing its prey. Its mandibles are actually more like a pair of hollow straws, and as it bites into the insect in the pit it injects a bit of venom, paralyzing that other insect. Now the doodlebug can impale it with its mandibles and suck out the body juices that it ingests, and once the prey is empty the doodlebug tosses its carcass back out of the pit. Depending on the species of antlion and the availability of food, it may require up to 3 years for the larva to complete its development. It then pupates, transforms to the adult insect, and these then may live another 3 or 4 weeks.

These are fascinating little insects, and they are harmless to humans and should be encouraged due to the benefit they provide in eating other insects. Some people capture the larvae and place them in a terrarium with the proper sandy soil and a food supply, and enjoy watching this little bit of nature in their own home.