Tireless brimstone lifts the spirits

Ross Bentley
Est. Reading: 3 minutes

Yellow is the colour of spring. Daffodils, dandelions, and early buttercups all lift the spirit on a walk across the Common Lands at this time of year. But there is one yellow that is particularly inspiring, the lemon tint of the brimstone butterfly, typically the first butterfly of the year to emerge and widely regarded as the ‘harbinger of spring.’

I saw one the other day on Little Fullingpit Meadow, taking advantage of a short interval of sun to jink and dart along the line of the river before heading off into the distance. Brimstones love the sun but will soon make themselves scarce if it clouds over, using their leaf-shaped wings as camouflage as they hunker down in clumps of ivy.

But when the brimstone is out and about, it seems to me they are always heading somewhere in a rush. Rarely do you see them stop and feed, and if they do, they do not take time to open their wings and enjoy the sun, like most other butterfly species. It is as if they are too busy to relax for a short time, they’ve got people to see, places to be. If the brimstone butterfly had a spirit animal, it might be the white rabbit from Alice in Wonderland.

The original butter-fly

And the word brimstone is highly evocative – an Old English term that literally means ‘burnt stone’ and the ancient word for sulphur. ‘Fire and brimstone’ is an expression used to describe the wrath of God but the sight of this yellow beauty in early spring seems to me to be one of the many glories of nature.

A friend who lives in the Pyrenees where the brimstone butterfly appears earlier in the year, keeps me informed of their emergence locally. In France the brimstone is simply known as ‘le citron’, the lemon. And the brimstone might in fact be the original butterfly as it is thought that the term butter-fly came about to describe the buttery yellow of the brimstone’s wing.

The mating game

The bright yellow brimstones we see in haste at this time are males who emerge from hibernation earlier than the females, who are much paler and tend to stay hidden away. Typically, they fly alone although I did see a pair flitting around and chasing each other in a sunny glade at Lackford Lakes near Bury a few weeks back. I could not work out whether they were playing and enjoying each other’s company or whether they were jealous rivals trying to intimidate their challenger.

The brimstone is one of a handful of our native butterflies that hibernate, emerging in spring as adults ready to mate. It is no wonder then that the brimstones we see look restless and full of vigour. They are males on the hunt for mates, patrolling for females to attract when they finally emerge. It is also no wonder then, when put like that, the females stay hidden away!!

The female will lay her eggs on buckthorn, the brimstone’s food plant, for the caterpillars to enjoy. The males and females, having created the next generation, will continue to fly and feed often into July before dying at about the same time that their offspring emerge from their chrysalis stage. This cycle means that the brimstone is in its adult stage for nearly a full year, making it Britain’s longest-lived butterfly.


But despite the brimstone’s all-round robustness, conservationists are concerned that the effects of global warming could threaten its existence. While it may be assumed that warmer temperatures are good news for the UK’s butterflies, many of which are on the northern limit of their natural range, the unpredictability of the extreme weather we are experiencing can play havoc. The unseasonably mild temperatures this winter have tempted spring butterflies out of hibernation early - our rangers photographed a brimstone nestled in ivy at their compound in mid-February.

These trends might throw the male butterflies out of synch with the emergence of the females or the timing of when buckthorn leaves are digestible. Couple this with more drought – that might hamper buckthorn growth - and heavy spring rains – butterflies hate rain - and it's clear the brimstone has a lot to deal with.

It would seem the greatest test of its resilience is yet to come.

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