By Rick Borchelt
You’ve probably seen them in the sand or loose soil under roof overhangs, beneath playground equipment or even right out in the open in the fine dust of baseball diamonds — alien-looking conical pits in the dirt, up to an inch wide and half an inch deep. They’re interesting to us — but deadly to ants.
These pits are the home of antlions, appropriately named pint-sized predators with massive jaws that lie in wait at the bottom of those pits, hidden in the sand with only the end of their massive jaws visible. Woe be to the ant that gets too close to the edge of a pit and slips in; the steep sides and fine grains of dust offer no leverage, and the hapless ant tumbles to the bottom. Its frenzy to escape only brings more sand down on top of it and alerts the waiting antlion that there is prey in its trap. The antlion quickly uses those long jaws to inject poison and solvents into the hapless prey to dissolve its internal organs.
Antlion pits are marvels of engineering. While they may appear to be uniform funnels of dirt to the casual observer, one side is always steeper than the others. It’s a perfect balance between collapse and stability; an ant that approaches the rim almost invariably causes the wall to collapse. If the ant doesn’t fall all the way in, the antlion uses its abdomen to flip a few grains of sand at the struggling victim, further destabilizing the wall and bringing the ant to the waiting jaws below.
Credit Rick Borchelt
While antlions have fearsome jaws, they don’t actually have a mouth — those long jaws consist of a fused mandible and maxilla, mouthparts that are usually distinct in most other insects. In antlions, this fusion creates a drinking straw with which they suck out the liquefied contents of their ant prey. (They don’t have an anus either, since all their food is liquid.) When the meal is finished and all that is left is the dried ant husk, the antlion simply flings it out of the pit, smoothes the walls and buries itself again at the bottom.
A common colloquial name for antlion larvae is doodlebug, and this moniker comes from how they move about. Antlions can only move backwards; all their powerful digging apparatus is in the muscular back end and legs. They travel just at or under the surface of the soil looking for an appropriate spot to dig a pit: usually in the shade and often under a surface that provides some protection from rain. Their wanderings leave seemingly random tracks in sand or dust — the doodles that give doodlebugs their name — tracks that begin to coalesce into a spiral and eventually a pit once the construction site has been selected.
Growing up in the Ozarks, I learned a chant from my grandfather that kids are taught to lure antlions into revealing themselves. While waving a very thin straw or grass blade in circles around the edge of the pit, we’d say, “Doodlebug, doodlebug, come and get your corn!” The straw would inevitably touch the side of the pit, or our breath would disturb the sand, rousing the antlion into thinking there was a struggling ant. It would reveal itself by throwing sand up the side at the fake ant and could then be plucked out of its pit.
Larval and adult antlions could not be less alike. Antlions adults are delicate, winged creatures related to lacewings. The female flies about on calm, late afternoons looking for loose soil in a likely location — probably using chemical cues to make sure there is an ant colony nearby — and broadcasts her eggs on top of the dust or sand.
Depending on the antlion species and how good their supply of ants is, the larval stage can last a few months or over winter. The mature larva spins a silk cocoon — very similar to the cocoons of moths — at the bottom of its pit. A winged adult emerges from this cocoon.
Our most common antlion is the spotted-winged antlion (Dendroleon obsoletus), whose pit traps you can often see in sandy soil along river banks and in abandoned sandboxes, among other places. But perhaps our most beautiful antlion doesn’t build pits at all. It’s the aptly named picture-winged antlion (Glenurus gratus), whose dazzling pink and black wings resemble stained glass. The larva is an ambush predator at the bottom of dry tree holes, burying itself in the accumulated debris and grabbing passing prey. The largest antlion in Maryland is the giant antlion (Vella americana). In Maryland, it’s only found on beaches in Worcester County, around Assateague Island, where it also forgoes digging pits in favor of lying in wait to ambush prey. Look for their trails across sandy paths in the dunes.
Antlions also have a firm place in the cinematic history of the Star Trek universe: They’re the model for the alien parasite that Khan puts in Chekov’s ear to render him biddable in “The Wrath of Khan”! youtube.com/watch?v=3i42Smtbmeg
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Have questions for Rick about the world of nature in and around the city, or suggestions for future College Park Wild columns? Drop him a note at rborchelt@gmail.com.
