PETER FROST takes to the Norfolk Broads in search of a real beauty.
I never need much of an excuse to take myself off to the Broads National Park. The park has its attractions all year round.
But from the end of May to mid July this amazing place has a bonus for those who love nature.
The Broads is home to Britain’s biggest and most spectacular butterfly – the huge and spectacular swallowtail.
The Broads is pretty much the only place in Britain where you have a good chance of seeing the swallowtail butterfly (Papilio machaon britannicus).
During much of the 20th century fenland management ceased, fen was drained for food production and much of the swallowtail’s habitat was lost.
The species went into slow decline and faced extinction.
Today active management and conservation of the Broads, where reed and sedge are cut to allow other plants to grow, plays an important part in the survival of the swallowtail, and many other rarities, in Norfolk.
With this continued fenland management, the future for the swallowtail looks brighter. Indeed the swallowtail is no longer rare in certain parts of the Broads National Park.
My top tips for spotting this splendid creature is to visit the Norfolk Wildlife Trust or RSPB Reserves at Hickling Broad, Ranworth Broad or Strumpshaw Fen. At the right time of year, in early morning on a bright summer’s day, then with luck you will spot one.
Some of my best sightings have been from the tiny and silent Electric Eel trip boat from How Hill.
Sightings here are quite common as the boat noses into the narrow drainage channels fringed with reed and sedge.
Indeed the butterflies often land on the boat itself as it cruises past patches of waterside milk parsley – the swallowtail’s food plant and the place it lays its eggs.
This is Britain’s largest butterfly with a wingspan of up to three or four inches (9cm).
Easily recognisable with its stunning yellow and black markings, it takes its name from its two long tail extensions which resemble a swallow’s tail.
These tails play an important part in the butterfly’s survival. Predators are confused by the tails which look like antennae and the two red and blue false eyes.
These look like another head on the back of the animal. Predators literally don’t know if the butterfly is coming or going.
Just hatched, tiny swallowtail caterpillars look like black and white bird droppings on the milk parsley leaves and stems, but as they grow, they become plump and bright green with black bands and orange spots along the body.
When threatened the caterpillar extends two horn-like bright orange scent glands emerge from the back of its head producing an unpleasant smell. Some say it resembles the odour of pineapple.
Today the swallowtail butterfly is almost totally limited to the fenland areas in the Norfolk Broads National Park.
It chooses breeding sites with a vigorous growth its only food plant, milk parsley. In summer it lays its eggs on the tallest of these umbrella shaped plants which often grow beside the drainage ditches, rivers and Broads.
The swallowtail spends the winter hibernating as a pupae at the bottom of the dried milk parsley plant stems. The eggs can even tolerate being submerged in water for long periods when river levels rise.
From late May as the weather warms up and sunny days become more common, adults emerge and will live for perhaps a month breeding and feeding. The first crop of adults have lived out their brief lives and are dead by mid-July.
In a good summer a second brood of adults may emerge in August. These will lay eggs and their caterpillars will form pupae in September and hibernate over the winter.
They will emerge again next summer to flutter among the golden reed beds of the Norfolk Broads. They are one of the most beautiful features of the amazing Broadland summer.
This article first appeared in the Morning Star Summer 2013