The brimstone (Gonepteryx rhamni) is among the earliest butterflies to take to the wing in the UK, and its sudden appearance on warm days is a welcome signal that the seasons are shifting. Although they are usually seen individually rather than in large numbers, brimstones are widespread and can be spotted across Hampshire and the Isle of Wight in gardens, woodlands, parks and along sunny hedgerows.
Adult brimstones are striking in both appearance and behaviour. Their distinctive, leaf‑shaped wings, complete with pronounced veining and pointed tips, are not only beautiful but practical. When the butterfly closes its wings, it blends so perfectly into surrounding foliage that it becomes almost invisible. Males display a vivid buttery yellow colour, while females are a much paler green‑white, each with a small orange spot marking the centre of their wings. It is thought that the bright yellow colour of the male brimstone's wings inspired the name 'butter-fly'.
Brimstones are unusual among British butterflies because they hibernate as adults. This allows them to be active throughout much of the year, even appearing in midwinter during mild spells. Most sightings, however, occur in early spring when newly awakened individuals begin feeding hungrily on nectar. Their preferred foodplants include early flowering species such as primroses and bluebells, and their long proboscis allows them to reach deep into tubular flowers that many other butterflies cannot access.
The life cycle of the brimstone is closely tied to two native shrubs: buckthorn and alder buckthorn. These are the only plants on which females lay their eggs and the sole food source for the caterpillars. The larvae are extraordinarily well camouflaged, matching the green of the leaves they feed upon. After developing through several stages, they pupate in summer, with new adults emerging from July onwards before settling down to hibernate through winter.
Although the brimstone is currently a common species, it still depends on healthy, connected habitats. Hampshire & Isle of Wight Wildlife Trust protects and restores wild places so that butterflies like the brimstone can continue to thrive. You can support this work by becoming a member. Visit hiwwt.org.uk/join-today or call 01489 774408 to help protect local wildlife all year round.
