Eyespots probably are eyespots after all. Moths really do try to fool birds into thinking they are staring at an angry cat or owl using fake “eyes” on their wings, a new paper shows.
The researchers cleverly manipulated the position of the white “sparkle” in the moths’ fake eyes. If the “sparkle” appeared in an unrealistic position, the moth was eaten.
Moths and caterpillars often display pairs of large dark circles. Tradition has it that these represent eyes – they are even called “eye spots”. But are these really meant to be eyes? Research shows that the patches cause predators to “startle”. However, there has been a recent
blazing row minor academic debate over whether these really are images of eyes.
On the one hand, many other moths achieve a “startle” response by flashing bright patches of colour, and the spots may be nothing more than brightly coloured patches. For example, one recent paper showed that birds avoid moth-like dummies with square or triangular patches just as much as they avoid dummies with circular patches, and that stripes are just as good protection as spots. Thus, it may simply be their conspicuousness that protects the moth, not their resemblance to eyes.
But an ingenious new study out last week has demonstrated that most moths with “eyespots” in fact use a clever illusion that makes it very hard to believe these are not meant to be images of eyes. Most “eyespots”, the authors found, have a “sparkle” – an off-centre white patch that looks like the highlight reflected by the surface of an eye. All cartoon eyes have a “sparkle”, for example – a simple way to enhance their realism.