Friday, 1 October 2010

A Plea to the Marsh Fritillaries of Wales

Life is precarious. Starting as a clutch of a few hundred eggs, mother marsh fritillary has laid you down on devil’s-bit scabious. When you hatch you are going to love this plant. In fact it’s the only thing you can eat, you are a very fussy eater. Your relatives in Europe eat honeysuckle but you won’t touch the stuff.

By late August, with the help of your surviving caterpillar brothers and sisters, you will have built a web low down in the base of the plant. On a sunny day, this makes a great bed to lounge on and admire the tall purple pom-poms and visiting bees while your plant is in flower.  In cold spells it’s best to climb down and huddle together beneath the tussocks.

With luck the marshy ground you live in will be grazed by cattle or ponies and not by sheep – they too are fussy with their food and will eat you out of house and home.

A large gang of caterpillars can soon demolish the leaves of a single plant and need to move on to the next one, preferably not too far away. Sometimes caterpillars are so prolific they eat the whole colony into extinction.

If you make it through winter into spring you will metamorphose into a pupa and emerge as a butterfly in early summer. Females are jumped on and mated immediately.

Your mother was not a strong flier to begin with and, laden down with so many eggs, her maximum range would be a hundred metres. This is why it is so difficult for marsh fritillaries to emigrate, you can only go in short hops, no question of a long haul to a landing field full of devil’s-bit scabious.

If weather conditions permit, your mother might have a second clutch of eggs – being a bit lighter, and with a tail wind, maybe she could manage a thousand metres?

You marsh fritillaries are a bit of a specialist that thrived on the back of a way of farming that is no longer in vogue. I’ll do what I can to help, by finding and protecting new sites, but the prospects are not good unless you can stop being so fussy with your food.

One theory is that you don’t eat honeysuckle because it’s too cold. Maybe you will be a winner from climate change.

1st October 2010 

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