I am writing a story that has insects the size of humans, but I am having a little trouble with the biology.

When you look up why there are no large insects on Earth, the most popular answer is that Square-Cube Law limits how large an organism their cardio-respiratory system could support. I feel like this is not that much of a problem to solve though. I just bump up the oxygen levels until things look about right and I'm done.

The problem I have is with molting. Each time an insect molts, it only grows a couple of centimeters. It would take decades just for my aliens to reach the size of a baby. Somehow, they need to grow an whole bunch every time they molt, and I cannot think of how.

In addition, for a while after an insect molts its new exoskeleton is much softer than it normally is. It is actually soft enough that if the insect is put into a confined space, its limbs will harden completely misshapen. Unless I make the gravity really low, the alien will not be able to support it how body weight.

Any ideas?

  • $\begingroup$ Interesting question. How big do you need them to be? 1.8m tall in average or can the great majority be peptite and only some Warrior caste merges 5 individuals for larger size? $\endgroup$
    – Gustavo
    Mar 1, 2020 at 15:44

2 Answers 2


They could have their moulting process in water, this provides a safer environment and supports the weight of the creature. Like lobsters once out of their exoskeleton they could absorb water to increase their size. They could have a special bath or safe body of water designed for the moulting period.

On a side note lobsters die because the larger they grow the more energy consuming moulting becomes. Lobsters can be considered biologically immortal as they don't seem to slow down or weaken with old age, it is the moulting process that kills them, if predators don't get them first.

http://www.veganpeace.com/animal_facts/Lobsters.htm https://en.wikipedia.org/wiki/Lobster#Longevity

  • $\begingroup$ You could also use a combination of the enzyme telomerase and peptide somatropin (growth hormone) or an equivalent to boost growth during moutling periods. $\endgroup$
    – user69935
    Mar 1, 2020 at 17:23
  • 2
    $\begingroup$ In addition to moulting in water, they could experience periods of extreme binge eating right before a massive sedentary moult, where they grow many more sizes than usual. Or they could form a protective cocoon to shield themselves while moulting for a period of time. $\endgroup$
    – Tardigreat
    Mar 3, 2020 at 8:37

It is possible that the insect like aliens might live in a microgravity space habitat with high oxygen content in the atmosphere (though great risk of fires). Possibly that habitat might have been constructed and their species created by a different, highly advanced alien society.


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