NATURE NOTES:

It looks like a bee, so it must be a bee, right? Well maybe not...

Thursday, 17th September 2020, 12:00 am

I’ve recently started studying hoverflies, which are fascinating group of insects. Amongst the 280 or so species that can be found in Britain, several look very much like bees, wasps or hornets, which are known as mimics because they have adapted to look like another species.

Mimicry is widespread in nature, you will find it in every habitat in every continent but you can also find it here, by your own backdoor. So why do creatures mimic - adapting themselves to look like other species, or even adapting parts of themselves to look like other parts?

Defence is the main reason, like the hoverfly that looks likes a bee or a wasp. The hoverfly isn’t dangerous at all to predators, but because it looks like something more dangerous, like a wasp with a nasty sting, would-be predators are more likely to leave it alone. Some creatures mimic another that tastes horrible or is poisonous, for example the harmless King Snake looks exactly like the deadly Coral Snake, a predator wouldn’t be able to tell them apart so leaves the King Snake alone.

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Other creatures can use mimicry as a way of making it easier to catch food; in America, Turkey Vultures generally eat the carcasses of dead animals rather than catching live prey and therefore living things don’t regard them as a threat and ignore them as they fly overhead. Zone-tailed Hawks do catch live prey. By blending in with the vultures Zone-tailed Hawks can catch their prey by surprise.

Many species of moth, butterfly and even fish have ‘eye markings’. These ‘eyes’ can make predators think they are being watched or, in the case of butterflies a bird might attack the eye marking on the outer wing, giving the butterfly time to escape albeit with a damaged wing, but this is preferable to being eaten.

Some larvae of moths and butterflies, especially caterpillars also use mimicry. The caterpillar of the Elephant Hawk-moth has a large swollen head with elaborate eye markings to make it look like a snake. This form of mimicry relies on the innate, hard-wired response of insectivorous birds to avoid snakes.

Although camouflage isn’t technically mimicry, mimicry is a form of camouflage. Many moths have adapted to look like bird-droppings and therefore unpalatable to predators. The small larvae of the Alder moth and several adult Tortrix moths reassemble bird poo. Other moths, like the Buff-tip moth have adapted to look like twigs from trees, others look like lichen to camouflage themselves.

Mimicry isn’t just visual, birds can mimic the sound, songs or calls of other birds – some have even learned to mimic door bells and mobile phones. Birds might mimic others to impress a would-be mate, to deter competition or to protect their nests of young.

Some mimics are remarkably accurate to their model whilst some are much less convincing, just using the basic colour scheme of more a dangerous creature for example, relying on the predators poor vision rather than perfect mimicry.

When we look closely enough, mimicry is all around us. Think of how the ‘own brands’ on the supermarket shelves look remarkably like the ‘leading brands’ next to them. Mimicry in nature is far more fascinating though, species adapting through natural selection over many thousands of years. It was this that so fascinated Darwin and others of his time, as it does naturalists today.