Antlions are really cool insects. They belong to the Myrmeleontidae family and most people are more aware of their larvae than the adults. The adults can be active at dusk but most are nocturnal, so if you don’t spend much time outside a night and you’ve never seen one – this might be why. When people do see them they are often confused with dragonflies, but you are far less likely to see a dragonfly at night.
Dragonflies and damselflies also have very short, pointy antennae (below, left) – while adult antlion antennae are much longer and end in a club (below, right). Antlions also have much more slender bodies when compared to a dragonfly. So, if is nighttime and you think you might be seeing a dragonfly, then just have a quick look at the antennae.
Antlions spend most of their lives as larvae – the adults only live for up to one month. The larvae, in contrast, can spend several years growing and preparing to transform, so it’s much easier to locate the larvae. Larvae can be found by looking for the tell-tale inverted cone-shaped pits in the sand and when you do find them they look as though about half of their body is their head and jaws!
The larvae are ambush predators that make these pits for uses as traps in which to catch their prey. They spend their lives buried in sand at the bottom of their traps with their jaws wide open waiting for lunch to tumble down into them. They are actually covered in lots of tiny hairs that help to keep them anchored in their pits and to give them purchase when capturing prey.
When not waiting for food they spend the rest of their time maintaining their pit traps. They both walk backwards using their abdomen (the rear bit of their body) like a plow to push the sand away into a circle and, once they are able to dig a deep enough cone, they also use their jaws like little shovels to scoop the sand and toss it up and out of the pit. The traps are made such that the sides are constructed of loose sand at its angle of repose – which means at the angle when it is JUST about to slide down with the smallest amount of movement. This way, if any unsuspecting prey items even get near the edge of the trap they quickly lose their footing and slide down into the waiting open jaws of the antlion larvae. Not only that, but the larvae actually throw sand at them in an effort to knock them down into their trap.
When a prey item does fall into their pit the antlion larva will quickly grab it with its giant sickle-shaped jaws. The jaws are huge and look a bit silly in comparison to the size of the rest of the body, but they are used for a lot and are important to the survival of the larva. The jaws are formed from the combination of the mandibles and another mouth part known as the maxilla. The mandibles (the pointy sharp bit on either side of the head) have deep grooves that run along their length and the way that the maxilla rests on top of the mandibles essentially creates a tube running from the pointy tips of the mandibles and to their base. Once a larva has prey in its mandible it can then inject venom that both immobilizes the prey and begins the digestion process. They don’t eat the hard exoskeleton part of their prey, instead they use those same hollow tubes running along their mandibles to suck up the now-liquified insides of their prey item like a buggy smoothie. Once the insides have been consumed the larva will flick the leftover husk up and out of their trap.
Once the larva is large enough it will pupate and undergo metamorphosis – holometabolous metamorphosis, so the adult will look completely different from the larva once the metamorphosis is complete. They spin cocoons of silk down in the sand and pupate for a little over a month. Once their pupation is complete it will emerge from the sand and inflate its wings and begin to search for a mate. The adults, as I said before, don’t live very long so it’s race to reproduce. Once females have mated they will find suitable sandy soil and will oviposit (ovi = egg and posit = place, so ‘lay their eggs’) their eggs directly in the soil. Once the larva hatches – the cycle begins anew.
Antlions are just super cool insects. Their larvae are such efficient and unique predators and the adults are gorgeous. Keep your eyes open at night, especially near lights, and make sure to have a look at sandy areas to see if there are any of the larval pit traps. I hope you’re all lucky enough to see one!
Also - please enjoy this YouTube! video I made:
A day in the life of an antlion larvae