Buttery butterfly

Let’s take a closer look at the most ‘butter’fly of butterflies…

It's early March and the sun is shining. The chill hasn't quite left the air but plants are growing, buds are bursting, bees are buzzing, birds are singing...spring is here. And with spring also come butterflies fluttering past. I've yet to see my first of the year but I know that it won't be long before the bright yellow of a brimstone flashes past.

Brimstone butterflies are the most butterley of all the flutterbies. Why? Because it's thought that the name 'butterfly' originates from this colourful species; the phrase 'butter-coloured fly', used to describe the bright yellow colour of the males, became 'butterfly'.

Brimstone butterfly resting on a leaf...and looking a bit like a leaf by Wendy Carter — Brimstone by Wendy Carter

Brimstone is another name for sulphur, which gives you another indication of just how yellow the males can appear; females are paler, almost lemony-green. You'd have thought that such colourful butterflies would stand out from vegetation but, with wings folded up above their bodies, they have the most remarkable ability to look just a leaf. This serves them well during winter when the adults tuck themselves away in evergreen foliage, resting until warmer weather returns.

They're one of few UK butterflies that spend the colder months as an adult, most others survive as an egg or as a caterpillar tucked up safe from the worst of the weather and predators. If you've got a dense stand of ivy or holly in your garden or local neighbourhood, there's a good chance that it's provided a winter shelter for brimstone butterflies as well as other butterflies, moths and more. Ivy is a great plant for wildlife so once persistent warmer temperatures arrive, you can safely prune it back to allow it plenty of time to produce flowers for autumn and berries and cover for next winter.

Yellow brimstone butterfly feeding on purple verbena flower by Wendy Carter — Brimstone on verbena by Wendy Carter

Could brimstone butterflies be harbingers of spring more than the return of cuckoos or the flowering of cowslips? Certainly their bright fluttering through our gardens, along our hedgerows and down woodland paths offer signs of warmth and colour to come. As they wake from winter slumbers, they seek out nectar-rich flowers to restore their energy levels. They'll play colour-snap with dandelions, primroses and cowslips as well as moving to bluebells and bugles as spring rolls on. There are two generations in a year and the summer generation have a preference for purples and lilacs - try attracting them where you live by planting verbena, betony, buddleia (dwarf varieties are available), teasel, thistle or scabious.

The next generation of butterflies don't happen accidentally. Once fuelled-up with nectar and the sun's rays, male brimstones patrol hedgerows and woodland edges looking for females. When a pair meet, they fly high into the air, circling around each other before tumbling into vegetation to mate. The female then hunts out buckthorn and alder buckthorn on which to lay her eggs; her youngsters are fussy eaters! It takes about two weeks before caterpillars hatch from the egg to eat the leaves of the plant. It then takes a whole month of munching before they pupate, undertaking the amazing process that transforms it into one of our most eye-catching insects.