Australian Walking Stick Insects Are Three Times Weirder Than You Think
The Australian walking stick is a master of deception, but a twig is just one of its many disguises. Before it’s even born, it mimics a seed. In its youth it looks and acts like an ant. Only when it has grown up does it settle into its final, leafy form. Along the way, it fools predators at every turn.
TRANSCRIPT
Our story begins with a seed, an ant, and a leaf. Or does it?
Each one of these is a phase in the life of the same creature.
The Australian walking stick.
Deep in the forests of eastern Australia, a seed drops from the canopy above. Foraging ants carry it down to their underground burrow. They snack on the nutritious cap, leaving the rest intact.
But this “seed” is a knockoff. It’s actually an Australian walking stick insect’s egg. Here it is next to a real seed the ants also brought into the nest. The delicious part of this real seed is called the “elaiosome,” and the same part on the egg is called the “capitulum.”
It’s an evolutionary strategy to get that egg underground. Why? Ant nests are just the right humidity for the developing egg, and are well-protected from parasites and predators.
Several months later, the egg hatches underground, and a stick insect nymph emerges from the nest. It runs, looking for safety in the foliage above. It has taken on a new disguise: as a red-headed spider ant. Not only does it look a lot like the ant — it also moves like one.
And even strikes a pose like the ant, curling its abdomen.
Looking and acting like an ant may save this nymph’s life. Predators tend to steer clear of ants. Ants swarm — sometimes they bite and sting — and most worker ants aren’t all that nutritious.
On top of that, red-headed spider ants taste like rotten coconut or bad cheese. These birds take a hard pass.
Upon closer inspection, the disguise doesn’t really hold up. But hey — it gets the job done. And it doesn’t need to last long.
The red on the Australian walking stick’s head fades in just a few days.
The nymph races upward, into the trees. After about a month, the insect begins to change yet again. It will molt six times as it perfects its final costume, as it grows into an adult.
That frenetic ant energy gives way to a gentle swaying — like a leaf in the breeze. Nothing to see here, predators.
The insects graze all day, mostly on eucalyptus leaves, plumping up and growing as long as your palm. Adults vary in color. Some even take on the green ruffled shape of a lichen.
You might think it’d be hard to find each other with all this camouflage, but they communicate with pheromones, so no problem. Sometime after mating, the female lays her eggs, which fall to the forest floor, and the cycle begins again.
The fake seed and pretend ant phases are more than just protection from parasites and predators. Since adult Australian walking stick insects don’t actually walk much, they rely on seed-collecting ants to disperse their eggs throughout the forest. Then it’s up to their zippy, ant-impersonating offspring to help them spread out even further.
The Australian walking stick insect has evolved so many looks, it almost seems like it’s having an identity crisis. But just because you can shape-shift from one form to another — and another — doesn’t mean you don’t know exactly what you are.
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