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August 2010 cover image Franklin Mountains

Wild Thing: Antlions

Antlions lie in wait for insects to fall into their funnel-shaped pits.

By Sheryl Smith-Rogers

Ever noticed networks of funnel-shaped pits dug into the sandy, shady soils of your yard? Though harmless looking, those pits — no more than 1 or 2 inches in diameter — are lethal traps, excavated by an odd insect called an antlion.

Elusive and sneaky, an antlion (Myrmeleon sp.) keeps a low profile throughout its life cycle. Larvae, not adults (more on them later), engineer the open pits that pockmark the loose, fine soils beneath trees, rocks and eaves of houses. At the bottom of each pit, concealed beneath a blanket of dirt, lurks an antlion.

Less than a quarter-inch long and grayish in color, an antlion larva can only crawl backward. Using its stout body, the larva plows through the dirt in search of an excavation site. In the process, an antlion — also called a doodlebug — may leave behind grooves that resemble doodling.

Photo by Grady Allen

Excavation of a pit begins when an antlion burrows into the dirt, then furrows backward in a circle. Digging deeper as it spirals downward, the antlion, using its flat head like a shovel, flicks dirt out of the way. When finished, the antlion stays burrowed and out of sight. With its sickle-like jaws poised for attack, the antlion waits for an ant, beetle or other small invertebrate to fall into the pit.

Once trapped, a victim tries to climb back out, but showers of dirt, flung by the antlion, thwart most escapes. Like a spider, the antlion bites its victim and sucks the paralyzed body dry, then tosses it out of the pit.

After pupating in the soil, antlions emerge as transparent-winged adults — drab brown with thick, clubbed antennae — that resemble damselflies. Reclusive to the end, adult antlions rest out of sight by day and flit around by night.

 

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