Extatosoma, an early runner

The story of a young spiny leaf insect on an escape trajectory.

Transcript

Picture yourself in an Australian jungle, in the middle of day.

[Australian jungle noise fade in]

Even though you are a stick insect, you are not yet in the canopy, but a few centimeters underground, in an ant nest, still inside your egg.

[Jungle noise muffles a bit]

It is getting about time to crack the egg, but you have a long journey ahead of you… To reach the trees.

Hi and welcome to the Insect Insights, chill insect stories to relax and wonder, now back from winter break! If you like this podcast, you can subscribe, leave a review and even an insect question. I am Max, your host, and I hope you are ready to dive into insect knowledge for another weekly insight!

It might sound surprising to hear that an egg ended up in this ant nest, but it is in fact rather common. Your egg bears a small structure, full of fatty acids ants adore. This small knob, the capitulum, is easily detachable, so ants can enjoy it without damaging your egg. They simply carry it for a while, often leaving it inside their nest once their snack is gone.

On one side, that give you safe condition to mature inside your shell. On the other side, it causes the first instant of your life to be complicated. So that the rest of yourself doesn’t end up as an ant-snack as well, you need to run, and run fast. Instantly after you are out of your egg, this is what you do. Run towards the light, and up.

Through generations and generations, hatchlings like you have been selected to look and move like ants, while still running without a stop. This made the escape slightly easier. If you make it out of the colony, good news! Your ant mimicking traits are still very useful, as predators usually don’t want to mess with ants. The other news is you are not done running, as you are still on the ground floor, and you want to reach the canopy.

More running, following the light and escaping gravity, for you. Until your first moult in a few days, you will keep climbing up trees. Even if you fall, you have tricks to glide down towards something you can grab onto. You are a small dedicated being. Committed with behaviour and morphology to one thing: going up.

Sources

Smart, H.R., Andrew, N.R. and O’Hanlon, J.C. (2023) ‘Ant mediated dispersal of spiny stick insect (Extatosoma tiaratum) eggs and Acacia longifolia seeds is ant-species dependent’, Australian Journal of Zoology, 70(4), pp. 105–114. Available at: https://doi.org/10.1071/ZO22036.

Suetsugu, K. et al. (2018) ‘Potential role of bird predation in the dispersal of otherwise flightless stick insects’, Ecology, 99(6), pp. 1504–1506. Available at: https://doi.org/10.1002/ecy.2230.

Zeng, Y. et al. (2015) ‘Visual ecology of directed aerial descent in first-instar nymphs of the stick insect Extatosoma tiaratum’, Journal of Experimental Biology, 218(14), pp. 2305–2314. Available at: https://doi.org/10.1242/jeb.109553.

Zeng, Y. et al. (2020) ‘Canopy parkour: movement ecology of post-hatch dispersal in a gliding nymphal stick insect, Extatosoma tiaratum’, Journal of Experimental Biology, 223(19), p. jeb226266. Available at: https://doi.org/10.1242/jeb.226266.