THE FIRST FLUTTER OF THE BUTTERFLY

BY ALICE MCDOUGALL (RSPB Volunteer)

Surely, a butterfly is one of the most enchanting sights of Spring - that flicker of colour, the delicate quivering wings - and then, in a flash, it’s gone, moving on to the next flower to extract its sugary nectar. This month look out for early arrivals: the bright yellow of the Brimstone, the Orange Tip, the Peacock, the silvery Holly Blue or the jagged wings of the Comma. But how do they make this journey to becoming a beautiful fluttering butterfly? We all know about the very hungry caterpillar, but what happens next?

During its relentless leafy feast, the caterpillar (larvae) will go through a sequence of skin moults stimulated by a hormone called ecdysone, eventually spinning itself into a chrysalis to hang from the underside of a leaf or rock. The body will then release enzymes called caspases which dissolve most of the cells and reduce the caterpillar’s body down to a mushy, soupy slush. The cells which survive this process are called imaginal discs and they do the work in forming the body parts of the butterfly – the wings, the eyes, the legs.

You might ask – how do we know all this? The groundwork for understanding metamorphosis started over three hundred years ago, and the person who pioneered this research may surprise you.

Maria Sibylla Merian, born in Germany in 1647, was a superbly talented naturalist and illustrator. In 1699, aged fifty-two, she defied all convention and set off on a two-month sea voyage to the South American country of Suriname.

This in itself is fascinating for a woman of her generation, but her expedition didn’t stop there. Merian trekked into the depths of the dark, tangled undergrowth of the rainforests, under the high canopies of the treetops, and immersed herself in the sheer abundance of Suriname’s flora and fauna. She meticulously observed, sketched and documented the process of metamorphosis in butterflies and moths, completing an important and influential catalogue of work.

So if you find yourself at Pagham Harbour or Medmerry admiring the ephemeral beauty of a butterfly, consider not only the incredible transformation it’s made, but also the intrepid journey Maria Sibylla Merian made in order for us to understand it.

Why not join us on one or our guided walks this month to look for signs of spring, including the first butterflies of the year? Find out more by visiting our website: https://events.rspb.org.uk/ paghamharbour or call 01243 641508.