Mimicry and warning in the insect world

Image: © Nevit Dilmen found at Wikimedia commons

Atlas moth. Image: © Nevit Dilmen, found at Wikimedia commons

Taking a break from the wonderful world of octopods, but still within the “amazing creatures” realm, I’d like to introduce you to some interesting mimicry and other colouration in the insect world.

Many insects can’t credibly threaten most predators, so they rely on protective colouration to escape detection or, failing that, to pretend to be something else that might pose a threat to the predator. A very common form of protection is camouflage, where the insect is coloured (and sometimes shaped) to blend in with a common background. The moss mantis is a fine example of this: both colour and shape mimic the moss that grows on trees where this insect is found, effectively hiding it from predators.

But that’s not as exciting as some of the other tricks that insects have come up with. My personal favourite is the Atlas moth, probably named because it’s the largest moth in the world – the wingspan can reach one foot across. That guy (or girl – the females are larger than the males) won’t just flutter around the lamp, it’ll grab the lamp and smash the window with it.

The real magic of the Atlas moth, though, is the wing markings: as you can see in the image, the wings look like a pair of rearing cobra heads. That’s enough to make any predator go quietly about other business, especially given the size of the moth. CarlyB at The Featured Creature has some even more impressive images of this moth, plus a video of one fluttering on someone’s hand, in this post.

That’s an example of mimicry, which generally involves one creature mimicking the appearance of another, generally one that’s either threatening, poisonous, or just distasteful, in order to deter predators. Another example of this, or a potential example, hit the internet recently – a fly with wings that look like ants or spiders. This little critter really appears to have a couple of passengers glued to its wings, but it may not be so simple: we may be seeing what we want to see (read this article for a full explanation of this).

Stinging Rose caterpillars. Image by Megan McCarty, in public domain

Stinging Rose caterpillars. Image by Megan McCarty, in public domain

Insects have still other weapons in their protective arsenals. They can announce that any predator trying to eat them will be very, very sorry (whether or not this is true – some non-toxic insects mimic toxic ones). They do this using bright, distinctive colours and patterns, which stand out against the background and make them the insect equivalent of a flashing neon sign.

This presents a bit of a problem in an evolutionary sense, though, because it requires predators trying to eat enough of the insects to learn to avoid them, while also requiring the simultaneous development of toxicity and protective colouring. If the insects were highly visible but non-toxic, they’d be eaten into extinction in short order. And if there were only a few with the toxic/colourful genetic mix, those would be eaten before the predators (the surviving ones anyway) learned to avoid them. So the insects need both a sufficient population base and possibly another trick in order to establish to predators that eating them is not worth the trouble.

So it’s a tough life being an insect, but given that roughly 80% of the species on Earth are insects, they’ve worked out plenty of ingenious ways to cope and survive. That’s a bit humbling, I think: humans think pretty highly of themselves, but evolution seems to have come down heavily in favour of things with more than four legs.

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One Response to Mimicry and warning in the insect world

  1. Pam Birchall says:

    Good morning Alison, Truly beautiful. I’m looking forward to the t.v. program on Ch. 7 on Sunday night.. Enjoy your day, Pam…………..

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