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Fred's Bughouse Blog: Antlions Part One

Updated: Apr 9

Hello and welcome to Fred’s Bughouse! Today’s insect du jour digs holes with one hand, appeared in Star Trek and Star Wars films, and lives most of its life without an anus. Intrigued? You’ll find our friend hanging out in the Bughouse...


Today we’ll be discussing the fascinating insect family Myrmeleontidae, a group known colloquially as antlions. This is one aptly named insect -- "antlion" is a 100% literal description of this unstoppable predator's feeding habits. We'll explore this topic, among other things, in today's post. If you're an ant, you will definitely need to have a drink in your hand.


Every bit as uncompromising as they appear: antlions, dorsal and ventral views.

(Wikimedia.org)


Antlions are actually the larval stage of an insect that undergoes complete metamorphosis – that is, they pass through stages that don't much resemble each other. In the case of the order Lepidoptera (butterflies and moths), the cute caterpillar becomes a beautiful butterfly. In the case of the Myrmeleontidae, the gnarly, violent larva becomes a harmless, fragile insect that sometimes flutters to lights at night like a depressed goth dragonfly. You have probably encountered antlion larvae in your time outside, or at least come across the conical pits they dig to trap other insects, but few people have seen – or at least noticed – the adult insect:


An adult antlion. They must look at their immature offspring and ask, "What did I do wrong?"


The antlion begins life, as do so many insects, as an egg laid by a mated adult female. Since they undergo complete metamorphosis, there are four basic life stages: egg, larva, pupa (or cocoon), and adult. Antlion cocoons are silky and round, and the graceful, long-winged adult insect that hatches out is puzzlingly larger than the larva that went in – a lot larger. In fact, antlions exhibit the greatest disparity in size between larva and adult of any insect, thanks to the fact that the adult’s exoskeleton is so thin and flimsy, while the larva is, well – let's just say they're "husky."


Antlion larvae are ambush predators who will grab, kill, and devour just about any insect out strolling past their lair. Many antlions just stand around until someone walks by, at which point they grab them and eat them...



Most antlions, however, have evolved a pretty spectacular method of catching prey -- they dig a pitfall trap in sandy soil and wait at the bottom for victims to fall in. The entire process bears some explaining, so let's break it down:


Step 1: The antlion wanders around until it finds a good place to dig its pitfall trap. As they walk — waddle, really — they leave characteristic squiggly tracks, which is why they're often called “doodlebugs.”

(That's right -- that adorable little doodlebug you loved in all your childish innocence is actually a remorseless predator with hollow fangs that it uses to grab innocent victims and inject cell-liquifying venom into their struggling, bleeding bodies. So it goes.)





Step 2: Once it finds a good spot, the antlion starts digging its pitfall trap. If you have ever tried to dig a hole many times bigger than your own body in dry sand with your bare hands (and who hasn’t?), you know that it’s not easy. The antlion gets it done WITH ONE HAND. It has devised a pretty cool work-flow: it digs in a spiral, and with one hand, or claw, it scoops dry sand onto the back of its wide, flat head and flips the load completely out of the hole. It works fast, too. Here's a satisfyingly zen video of an antlion at work:



Step 3: Once it has the pit to its liking, the bug squirms backwards into the bottom. It’s a chubby little beast, but its head is flat and camouflaged. Once it squirms all the way ass-backward into the pit, all that sticks out are the insect’s enormous, sickle-shaped jaws, which it opens as wide as it possibly can.


Step 4: An ant or similar unlucky insect walks by and tumbles into the pit of dry sand. The walls give way as it frantically tries to scramble out, but all that its desperate clawing accomplishes is to bring it closer and closer to the center of the pit, where the gaping, venomous jaws of the antlion are waiting. Things get worse for the insect as the antlion begins flinging loose sand at its struggling prey, further collapsing the walls and making escape virtually impossible. The victim is doomed.


UNLESS…


Step 4A: It’s not a victim at all. Some other bugs hack the antlion’s system. One kind of parasitic wasp plays it the right way – it intentionally allows itself to be caught by the antlion, but before it gets eaten up, it lays an egg right on the antlion’s exposed neck and flies away unscathed.


Step 4B: The baby wasp grub hatches out and burrows into the antlion’s body and eats him alive from the inside out. Score one for Team Victim!



BUT MORE LIKELY...

Step 5: Once the target is within reach, the antlion grabs it and punctures its body with its gigantic fangs. Venom flows from channels in each pincer, and the insect is immobilized in seconds.


Step 6:. The antlion, like a spider, uses its fangs to suck out the poisoned, liquified insides of the insect, and then gives the empty husk a header over the edge of the pit.


Step 7: The antlion burps and scoots its chubby butt backwards into the pit and begins the wait for its next meal.


Spot the killer!


If this were all there was to know about antlions, we would already have a truly exceptional little bug on our hands. But there's more. Much, much more, and we'll get into that in Fred's Bughouse Blog: Antlions Part Two...


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Sources:

Wikimedia.org

https://macroinstantes.blogspot.com/2013/09/larva-de-crocinae.html

https://aggie-horticulture.tamu.edu/galveston/beneficials/beneficial-32_ant_lion.htm

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All images public domain/Wikimedia Commons unless otherwise noted.