Nature to look out for in Burwell

The caterpillars of peacock butterflies – surely one of our most stunning butterflies – can be easily spotted on one of the sunny clumps of nettles at Spring Close now! Tipped off by Caroline, I went looking for them on the clumps of nettles that edge the spring. Soon at about chest height, I saw a wriggling mass of velvety black bodies happily chumping on the leaves and flowers of a large clump of nettles.

I watched as they crawled under and over each other, or reached out, waving their outstretched bodies in search of the next bit of nettle to grab onto to find another juicy bite to eat. It is possible to see them well with the naked eye, but next time I will take a magnifying glass to appreciate even better the intricacy of their colour, their punk like spikes and munching mandibles.

Female adult peacocks take up to two hours to lay clumps of hundreds of eggs on the underside of nettle leaves. After two weeks, these eggs hatch into these voracious caterpillars. They need to eat fast as at this stage they are particularly vulnerable to predators. Once the caterpillars have sufficiently stuffed themselves, they disperse to form a chrysalis, which hangs downwards from a silken pad. Extraordinarily, the colour of the chrysalis varies according to its location, to maximise its camouflage and so its chances of survival.

After around two weeks a magnificent peacock butterfly emerges. Soon we will see these butterflies in their fresh plumage, flying round our gardens, feeding on nectar rich flowers. Come September they will find a place to hibernate, tucking themselves away in a sheltered corner, until next March when they will emerge, feed up, lay their eggs and then die.

In the human world nettle patches often are regarded as a sign an area is neglected. In the non-human world such patches are home – providing cradle and food – to lots of creatures. When we do ‘a bit of tidying up’, the home for any one of the stages of the incredible process that results in the emergence of stunning peacock butterflies, is so easily and unwittingly destroyed.

Now to the fun bit – the poo! The nettle leaves under the mass of wriggling peacock caterpillars mass were covered in frass, the polite word for insect poo. I suggest pointing this out to get the interest of any child – which includes us adults, or me at least! Peacock caterpillars happen to be easy to spot. However, often caterpillars and larvae are very well camouflaged. Looking out for and spotting frass then becomes key to knowing they are present, and so being able to find them.

Thanks to Richard Lewington’s brilliant ‘Pocket Guide to the Butterflies of Great Britain and Ireland’ (BWP) for information on peacock butterflies’ lifecycle.

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