Eyespots and the amazing Macrocilix maia

I am continually astonished by anti-predator defences in insects. One day it might be an insect that is so well camouflaged that you struggle to find only even when you are literally inches away. The next day it could be an astonishing mimic like a fly that mimics a bumble bee. Of course eyespots have their own appeal; conspicuous circular markings that resemble eyes, usually in direct contrast with the rest of the animal's body which is amazingly well camouflaged. Eyespots with an anti-predator function have been described in fish, birds, amphibians, and of course insects. Some of the best known examples come from Lepidoptera (butterflies & moths).

Today I found some beautiful adult moths from the genus Automeris (Saturniidae). When threatened they have the interesting behaviour of spreading their forewings and revealing otherwise-hidden eyespots. To get a sense of what this behaviour I gently prodded a few. The moths spread their wings and showed off their eyespots, sometimes in doing so they fell to the ground. Even as they fell, and upon landing, they held those wings open. After roughly 2-3 minutes the wings slowly returned to their natural "tent" resting position. Subsequent prods sometimes would elicit the behaviour again, but usually initiated an escape flight response instead. This is what they look like:

Recently there has been discussion over a new and unique type of colouration on the wings of an adult Lepidopteran. The descriptions of this species from Boneo and Malaysia are borderline unbelievable.  I have to say that I was skeptical (to say the least) when I heard the descriptions. If you look hard enough at something you can often see amazing things that arn't really there.

Without tainting your view by telling you what other people see have a look at some of these photos of the moth Macrocilix maia:

When you see the photo it really is amazing. The accompanying descriptions are just as interesting. Right now there is rampant speculation on exactly what these colour patterns are supposed to resemble. Jerry Coyne has a great blog post on it here. Read the comments below his post to see some interesting ideas.

Some are suggesting that it could be a phenomenon new to biology: mimicry of an entire scene. Currently, my view is that this is a form of masquerade: a moth that with descrete, high-contrasting markings that seem to vaguely resemble flies buzzing around a piece of feces/rotting flesh. This probably protects the moth by causing the predator to misclassify it as an inedible object(s). It seems possible that a predator big enough not to be interested in eating little flies should pass over it, but anything small enough to want a fly might not be able to subdue a big moth.

Some preliminary questions are left in my mind though:
  • Wouldn't this moth have to rest on a white background for this to work, and where are these white backgrounds?
  • There are flies and discrete piles of decaying crap elsewhere, why don't we see similar adaptations elsewhere?
  • Does the moth move its wings to simulate buzzing flies?
As always, your thoughts and comments are welcome below, just click the "comments" link below this (or any other) post to leave a message.


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