Sunday, 2 February 2014

Brimstone 2014

Brimstone (Gonepteryx rhamni)

The adult brimstone butterfly is one of the first woodland butterflies to emerge from winter hibernation. I have often seen them on those sunny days in mid March that herald the promise of spring. The bright yellow males are the first to emerge and their busy patrolling flight up and down the woodland rides is a familiar addition to the resurgent spring greenery.

The adult females emerge after the males and after mating they begin their search for buckthorn (Rhamnus cathartica) or alder buckthorn (Frangula alnus), the larval foodplants of the Brimstone butterfly here in East Sussex.

Brimstone: Photo Douglas Neve 2014

Brimstone butterflies are well distributed throughout East Sussex. They generally have a preference for woodland but female brimstones will often be seen away from woodland, patrolling along hedgerows, in gardens and on wasteland, as they search for the plants upon which to lay their eggs.

East Sussex Distribution Map 2013

The weekly total count of adult Brimstones in the years 2011, 2012 and 2013, for the whole county of Sussex, obtained from the Sussex Butterfly Conservation Records Database, is shown in the bar chart below.

Two features are very noticeable. Firstly there are twin peaks in the count numbers each year, with a local maximum occurring in the spring (weeks 12 to 25) and another in the mid to late summer (weeks 31 to 37). In between (weeks 26 to 30) there is a bit of a lull and this corresponds approximately with the time that the offspring of the spring brood of Brimstones take to mature from egg, to caterpillar, to pupa to second brood adult.

The other striking feature of this chart is that it illustrates how the warm, dry spring of 2011 resulted in a high adult Brimstone count and similarly how the warm, dry summer of 2013 resulted in relatively high count too. However I will add a note of caution about these values, as favourable conditions could also mean that more Butterfly recorders were out in the good weather than would of been the case if the weather had been poor.

Brimstone: Photo Douglas Neve 2014
So if the rain ever stops and when the sun shines again, keep an eye out for the Brimstone, one of the first butterflies of the year.

Please note too that there are still quite a few tetrads where this butterfly could be present but has yet to be recorded.


Still rather wet out and we are not done with the winter yet by any means;
Barnes Wood Mud: Photo Jim Barrett 2014

 The little streams fill the big streams
A Clear Water Stream: Photo Jim Barrett 2014

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