Brimstone butterflies

Posted: Wednesday 1 January 2014
by Richard Jones

Happy new year. Or, from a more biological point of view, Happy random arbitrary date somewhere near the middle of winter.

Happy new year. Or, from a more biological point of view, Happy random arbitrary date somewhere near the middle of winter. It is pretty arbitrary, isn’t it? The winter solstice, around 21 December (coincidentally very near Christmas day) is at least a measurable seasonal event, with major implications for both the agriculture and psychology of the early civilizations which first formalized our calendars.

The wildlife out there is not really going to jump out of hibernation bed today. Except there is one insect which is supposedly renowned for doing this. The brimstone butterfly, Gonepteryx rhamni is one of only five UK species which hibernate as adults (small tortoiseshell, peacock, comma and maybe the red admiral are the others). Folding its delicately sculpted wings together it looks just like a dead leaf as it hides in the ivy thicket or some other dense evergreen. Here it waits until sunny days of spring.

There are reports of brimstones being roused by mid-winter sunshine falling on the roost; a butterfly takes to the air to fly over bright sunny snow for a short while, but retires quickly as soon as the sun goes in or down, and returns to winter torpor until spring really arrives in April.

The brimstone is one ‘common’ butterfly I hardly ever see in south-east London; in fact I’ve only ever seen one, bowling down our street at top speed one summer day a few years ago. This says much about brimstone ecology. Brimstones are notoriously tied into the occurrence of their foodplants — buckthorn (Rhamnus cathartica) and alder buckthorn (Frangula alnus), so their distribution at the local level is very patchy, but they are also strong fliers, and the males seem especially mobile, scooting off many kilometres during the peak emergence periods in April/May and again in August.

The British distribution of brimstones (England to Yorkshire and Lancashire, lowland Wales and parts of central Ireland) perfectly matches the distribution of its foodplants, but it has been spreading north in the last 20 years. This is in response to amenity planting of buckthorns in ornamental gardens, supermarket car parks and urban parks, showing that growing one or other of these bushes in the garden really can benefit the butterfly.

So if you’re looking for a good and useful New Year Resolution to make today, why not resolve to plant a buckthorn, in the hope of seeing this lovely insect and its equally lovely sleek green caterpillars?

Many thanks to Matt Berry, Butterfly Conservation, for kind permission to use his beautiful image.

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Talkback: Brimstone butterflies
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higgy50 02/01/2014 at 17:44

A brilliant piece Richard and demonstrating what we can all do very easily in our own gardens - Grow the right plants for the right species!

With a little bit of homework and the help of the internet, it is very easy to find what species exist in your own local area and then match the food plant. However we must remember the food plant for the caterpillar is often different to an adult butterfly. It is this larval food plant that we need to consider on top of the pollen rich flowers that we all usually associate with butterflies.

Last winter I planted several Alder Buckthorn bushes in among my native hedgerow that I am currently trying to develop. To include these types of 'larval' food plants in a planting scheme such as a native hedgerow is an easy way to include them in your garden and of vital importance to the long-term survival of many species. Therefore I support your sentiments for every gardener to plant at least one Buckthorn or Alder Buckthorn in their garden. Together we can all make a real difference!!
Best regards

nutcutlet 02/01/2014 at 18:24

 These peacocks though they were hibernating in the woodshed but had to be rehoused if not to be burnt

higgy50 03/01/2014 at 16:50

Good to see a good number and someone who is prepared to take the time to move them. Good Work!!

Where did you relocate them out of interest? Was it another shed or a butterfly box or somewhere completely different?


nutcutlet 03/01/2014 at 16:54

They're back in the woodshed but out of the danger zone.

This place is more nature reserve than garden higgy.

But I haven't seen any Brimstones on the move.

higgy50 03/01/2014 at 17:07

Sounds like my dream garden (a nature reserve!!) My garden is the same and I've been trying to get more wildlife in since we moved in four years ago.

I was really pleased to reach 20 different species of butterfly recorded in the garden last summer and these do include the Bimstone! LOL

My last sighting was this Red Admiral on 30th November.



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