Brimstone (Gonepteryx rhamni)
The brimstone is a large, leaf-shaped yellow butterfly of woodland edges, hedgerows and gardens across Europe, North Africa and temperate Asia, and the male's uniform sulphur-yellow wings — each carrying a single small orange spot and always held closed at rest — are its defining mark. It is also one of the longest-lived butterflies in the world: the adult hibernates through the winter inside evergreen cover and may live ten months or more, which is why a brimstone is so often the first butterfly on the wing on a warm day in early spring.
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In this guide
Description and identification
The brimstone belongs to Gonepteryx, a small genus of yellow butterflies in the subfamily Coliadinae of the whites and sulphurs family. It is one of the easiest European butterflies to name, because no other large butterfly in its range is a plain, even sulphur-yellow with wings shaped like a leaf. Both the forewing and the hindwing are drawn out into a short point, the veins stand out as pale ribs, and the outline of a settled brimstone is so close to that of a leaf that the butterfly can be looked straight at and missed.
Adult butterfly
- Wingspan: 2.2–2.9 in (55–74 mm), making it one of the larger butterflies of European hedgerows and noticeably bigger than the common whites it flies with.
- Upperside: the male is a strong, uniform sulphur or lemon yellow with no dark border and no dark veins. The female is very different — a pale greenish-white that can look almost plain white in bright sun. Both sexes carry one small orange or orange-red spot in the centre of each of the four wings.
- Underside: a duller, greener version of the upperside, with the veins raised and picked out in a paler tone and the orange spots repeated. The green of the female's underside is stronger than that of the male.
- Wing shape: the key structural mark. Each wing ends in a small hooked point, and the margins are slightly scalloped, so the closed butterfly has the outline and the vein pattern of a leaf rather than the rounded fan of a white.
- Body: slim, with a dark, finely haired thorax, pink-tinged antennae with small clubs, and an unusually long proboscis for a butterfly of this size.
- Sexes: easily separated in the field. Yellow means male, greenish-white means female — one of the clearest cases of sexual dimorphism among European butterflies.
Across its very wide range the brimstone varies little, and the handful of named subspecies differ mainly in size and in the depth of the male's yellow. Butterflies from southern Europe and Asia Minor tend to be larger and more strongly coloured than those from the north, but the pattern is the same everywhere.
How to identify a brimstone in the field
Start with the flight. A brimstone flies strongly and purposefully, usually a metre or two above the ground, following a hedge, a woodland ride or a garden boundary, and it rarely stops. If a large plain yellow butterfly sails past a hedgerow in March, it is almost certainly a male brimstone, because very little else is flying. When it does settle, it always closes its wings — an adult brimstone is never seen basking with the wings spread — so the field marks to check are the leaf-shaped outline, the raised veins, and the single orange spot on each wing. Pale females are the usual source of error and are regularly recorded as a cabbage white; the wing shape settles it instantly, as the whites have rounded wings with black tips and no hook.
Life cycle: egg, caterpillar, chrysalis and adult
The brimstone has one generation a year and an unusual calendar: the adult, not the egg or the pupa, is the stage that survives the winter. Fresh butterflies appear in midsummer, feed, hibernate, and then do all of their breeding the following spring, which is why the same individual can be seen in July and again in April. The four stages below are the ones photographed on this page, and each one follows the same complete metamorphosis seen in every butterfly.
Eggs
A female searches out buckthorn by scent and by sight, often flying several kilometres between bushes, and lays her eggs singly on the underside of a young leaf or on a leaf bud, usually choosing a sheltered, sunlit bush at the edge of a thicket rather than one in deep shade. Each egg is about 1.3 mm tall, skittle- or spindle-shaped and finely ribbed along its length. It is greenish-white when first laid, turns yellow within a day or two and then greys shortly before the caterpillar chews its way out, which takes one to two weeks depending on temperature.
Caterpillar
The newly hatched larva is dull grey-green and less than 2 mm long. As it grows it becomes a matt bluish-green above and a paler, almost white-green along the sides, separated by a fine white line running through the spiracles, and the whole surface is covered in minute black points and short hairs. There are five instars, and the full-grown caterpillar reaches about 1.4 in (35 mm) after roughly four weeks of feeding. Its habits are as good a field mark as its colour: it rests stretched out along the midrib on the upper surface of a buckthorn leaf, where its green matches the leaf exactly, and it eats from the leaf edge inwards, leaving a characteristic ragged notch. It is harmless to handle and has no spines or stinging hairs.
Chrysalis
The caterpillar leaves the food plant and pupates low down on a stem or on nearby vegetation. The chrysalis is 0.9–0.95 in (22–24 mm) long, pale green with a yellow line along each side and a few small dark marks, and it is held upright against the stem by a silk girdle around the middle and a hooked cremaster at the tail. Its swollen, sharply pointed shape is another leaf imitation, and it is exceedingly hard to find. The pupal stage lasts about two weeks; a day or so before emergence the wing cases darken and the yellow of a male, or the white of a female, shows through.
Adult
Adults emerge from late June onwards, feed hard on summer flowers to build up fat reserves, and by late August most have gone into hibernation among evergreen leaves. They reappear on the first warm days of the new year — often in February or March, sometimes as early as January in mild winters — and it is then that courtship, mating and egg-laying take place. A brimstone that emerges in July and dies the following June has lived some ten to thirteen months as an adult, far longer than the two or three weeks typical of most butterflies; our guide to how long butterflies live puts that figure in context.
Where the brimstone butterfly lives
The brimstone is one of the most widely distributed butterflies of the Palaearctic. Its range covers almost all of Europe apart from the far north of Scandinavia, reaches North Africa in the Atlas mountains, and runs east through Turkey and the Caucasus across temperate Asia to Siberia and Mongolia. In Britain it is common in England and Wales, expanding northwards in recent decades, and in Ireland it is concentrated in the limestone districts of the west; the butterflies of the United Kingdom include no other species that can be confused with a flying male. It does not occur anywhere in the Americas.
Its distribution is really the distribution of two shrubs. Wherever purging buckthorn or alder buckthorn grows, the brimstone can breed; where they are absent it can only wander. That ties it to open, damp woodland, scrubby grassland on chalk and limestone, fen and carr, hedgerows, old quarries, railway banks and large gardens. Adults, however, range far more widely than the breeding habitat, and a brimstone drinking from a garden buddleia may have hatched on a buckthorn several kilometres away.
For hibernation the butterfly needs something quite different: dense evergreen cover that holds its leaves all winter. Ivy, holly, bramble and dense tussocks of grass are the usual choices, and the butterfly wedges itself among the leaves with the wings closed, where its veined, leaf-green underside makes it almost invisible for four or five months.
Host plants and diet
Caterpillar host plants. Brimstone larvae eat only two host plants across most of the range: purging buckthorn (Rhamnus cathartica), a shrub of dry chalk and limestone soils, and alder buckthorn (Frangula alnus), which prefers damp, peaty ground. A few other Rhamnus species are used in southern Europe and Asia. This narrow diet explains almost everything about the butterfly's distribution, and it is also why planting a single buckthorn in a garden within the species' range is one of the most reliable ways of attracting a breeding brimstone.
Adult diet. Adults drink flower nectar and nothing else; they are not pollen feeders and they do not normally take rotting fruit. What sets them apart at the flower is the proboscis, which is long even for a large butterfly and lets the brimstone empty deep tubular blooms that most species cannot reach. Spring individuals work primrose, cowslip, dandelion, bluebell, ground ivy and sallow catkins; summer adults concentrate on nectar-rich purple flowers, especially teasel, thistles, knapweed, scabious, runner beans and buddleia, and they feed heavily before hibernation to lay down the fat and the sugars that must last them through the winter.
Behavior: hibernation, flight and courtship
Hibernation. The brimstone is the classic overwintering butterfly. From August it stops feeding, settles deep inside an evergreen shrub and enters a true dormancy that can last five months or more. Its body fluids carry high concentrations of protective sugars and alcohols, so the butterfly tolerates being frozen solid and a hibernating brimstone can be encased in ice and still fly a week later. The insect does not build any shelter; camouflage and chemistry do the whole job.
An early spring flight. Because the adult is already fully formed, the brimstone does not have to wait for warmth to develop — it only has to wake up. A single sunny day in late winter is enough, and in most of Europe the brimstone shares with the small tortoiseshell and the peacock the distinction of being the first butterfly recorded each year. Males emerge from hibernation before females and are the yellow flashes seen crossing gardens in March.
Flight and dispersal. The flight is fast, direct and strong rather than fluttering, with the butterfly holding a steady line along a hedge or a woodland edge and only rarely hovering. Brimstones are great wanderers: marked individuals have been found many kilometres from where they were released, and the species regularly appears in places with no buckthorn at all. That mobility lets it colonise new buckthorn thickets quickly and is one reason its range has been creeping north.
Courtship and mating. Pairing takes place in spring, after hibernation. A male detects a female visually and follows her closely in a slow, side-by-side flight, and the pair may travel a considerable distance together before the female settles and accepts him. Unreceptive females refuse by raising the abdomen steeply and holding the wings shut, a rejection posture that ends the chase; the general pattern is described in our guide to how butterflies mate and reproduce. Mated females then spend weeks searching out buckthorn, laying only a few eggs at each bush.
Defence. The brimstone has no toxins. It relies entirely on looking like a leaf, on settling only with the wings closed, and on a flight fast enough to leave most small birds behind.
Similar butterflies and how to tell them apart
| Species | Looks like | How to separate it from the brimstone |
|---|---|---|
| Cleopatra, Gonepteryx cleopatra | Almost identical shape and the same yellow ground colour | The male has a large orange flush across the centre of each forewing; a Mediterranean species that does not reach northern Europe |
| Clouded yellow, Colias croceus | Another large yellow butterfly of open ground | Deeper orange-yellow with a broad black border on the upperside, rounded wings with no hook, and a dark-edged silver spot on the hindwing underside |
| Cabbage white, Pieris rapae | Pale females are routinely mistaken for it | Rounded wings with grey or black tips and black spots, no hooked point, no orange central spot, and a much weaker, more fluttering flight |
| Green-veined white, Pieris napi | Greenish veins on the underside, like a female brimstone | Smaller, with rounded wings and grey-green veins on a white ground; the brimstone's veins are raised pale ribs on a green wing that ends in a point |
| Clouded sulphur, Colias philodice | The North American yellow butterfly people compare it to | A different genus on a different continent: black-bordered wings, rounded outline, and no brimstone occurs anywhere in the New World |
Quick facts
| Scientific name | Gonepteryx rhamni (Linnaeus, 1758) |
|---|---|
| Family | Pieridae (whites and sulphurs), subfamily Coliadinae |
| Wingspan | 2.2–2.9 in (55–74 mm) |
| Distribution | Europe except the far north, North Africa, and temperate Asia east to Siberia and Mongolia |
| Habitat | Open damp woodland, scrub, fen carr, chalk grassland, hedgerows and gardens where buckthorn grows |
| Host plants | Purging buckthorn (Rhamnus cathartica) and alder buckthorn (Frangula alnus) |
| Adult food | Flower nectar only, taken from deep tubular flowers with an exceptionally long proboscis |
| Lifespan of adults | About 10–13 months, including a hibernation of four to five months |
| Broods | One a year; adults fly in summer, overwinter, and breed the following spring |
| Defence | Leaf mimicry, permanently closed wings at rest and a fast, direct flight; no toxins |
| Conservation status | Common and widespread; scarce and legally protected in Northern Ireland |
Did you know?
- The name comes from "brimstone", the old English word for sulphur, a direct reference to the male's colour.
- Many writers trace the word "butterfly" itself to this species — the butter-coloured fly of early spring. It is a plausible and often repeated origin rather than a proven one, but no other candidate fits as neatly.
- Ten to thirteen months is an extraordinary adult life for a butterfly. Only a few species, such as the overwintering tortoiseshells and the pollen-feeding tropical longwings, come close.
- A hibernating brimstone can freeze. Cryoprotectant compounds in its body fluids stop ice crystals from destroying its tissues, so the butterfly survives spells that would kill most insects outright.
- Neat semicircular notches eaten out of buckthorn leaves in June are a reliable sign that a brimstone caterpillar is, or recently was, on the bush — often easier to find than the perfectly camouflaged larva itself.
- The butterfly is legally protected in Northern Ireland under the Wildlife (Northern Ireland) Order 1985, where it is confined to a small number of sites.
- Unlike the little yellow and the California dogface, two New World sulphurs that fly in several overlapping broods, the brimstone squeezes its whole year into a single generation.
In summary
The brimstone, Gonepteryx rhamni, is a large Pierid butterfly of Europe, North Africa and temperate Asia, recognised by leaf-shaped wings with hooked tips, a single orange spot on each wing, and a male that is plain sulphur-yellow while the female is greenish-white. Its caterpillar is a matt green larva that feeds only on buckthorn and alder buckthorn, its chrysalis is a green leaf-mimic held to a stem by a silk girdle, and the adult flies in a single annual brood, hibernating in ivy or holly through the winter and breeding the following spring. Ten to thirteen months as an adult makes it one of the longest-lived butterflies anywhere, and its early appearance has made it a traditional first sign of spring.
Brimstone butterfly pictures
Frequently asked questions about the brimstone butterfly
How can you tell a male brimstone butterfly from a female?
Colour separates them instantly. The male is a strong, even sulphur-yellow, while the female is a pale greenish-white that can look almost plain white in sunlight. Both sexes are the same size and shape, with hooked wingtips and one small orange spot in the centre of each wing, and both settle only with the wings closed.
What does a brimstone butterfly caterpillar look like?
The caterpillar is a matt bluish-green above with a paler, whitish-green lower half, divided by a fine white line along the spiracles, and its skin is covered in tiny black points. It grows from under 2 mm at hatching to about 35 mm, and it rests stretched along the midrib on the upper surface of a buckthorn leaf, where it is very hard to see.
How does the brimstone chrysalis avoid predators?
The chrysalis survives by imitating a leaf. It is 22 to 24 mm long, pale green with a yellow line down each side, swollen in the middle and pointed at both ends, and it is fixed upright against a stem by a silk girdle. Hidden low in vegetation away from the buckthorn itself, it is one of the hardest European pupae to find.
Where do brimstone butterflies live?
Brimstones live across almost all of Europe apart from the far north, in North Africa, and eastwards through Turkey and the Caucasus into temperate Asia as far as Siberia and Mongolia. They breed only where buckthorn or alder buckthorn grows, so they are found in open damp woodland, scrub, fens, chalk grassland, hedgerows and gardens.
Is the brimstone the origin of the word butterfly?
Quite possibly. The most popular explanation for the word is that early observers named the butter-coloured fly of spring, and the male brimstone is the only common European butterfly that is genuinely butter-yellow. The derivation is traditional rather than proven, but it remains the best-supported suggestion and is still widely repeated.
What do brimstone butterflies eat?
Adults drink only flower nectar. Their proboscis is unusually long, so they can empty deep tubular flowers such as teasel, thistle, knapweed, scabious and buddleia in summer, and primrose, cowslip, bluebell and dandelion in spring. The caterpillars eat nothing but the leaves of purging buckthorn and alder buckthorn.
How long does a brimstone butterfly live?
An adult brimstone lives about ten to thirteen months, which is among the longest lifespans of any butterfly. It emerges in midsummer, feeds for a few weeks, hibernates from late August until the following February or March, then mates and lays eggs in spring before dying in early summer, after one full turn of the year.
Where do brimstone butterflies go in winter?
They hibernate as adults in dense evergreen cover, most often deep inside ivy, holly, bramble or a thick grass tussock, a metre or two above the ground. The closed, vein-marked wings look exactly like a leaf, and the butterfly's body fluids contain natural antifreeze compounds that let it survive being frozen.
How big is a brimstone butterfly?
The wingspan is 2.2 to 2.9 inches, or 55 to 74 millimetres, which makes it clearly larger than the whites it shares hedgerows with. Southern and Asian populations tend towards the top of that range. Despite the size it is a light insect, and its strong, direct flight can carry it several kilometres in a day.
Is the brimstone butterfly poisonous or harmful?
No. The brimstone stores no toxins, does not sting or bite, and its caterpillar has no irritating hairs or spines, so both are completely safe to handle. It relies on camouflage instead, imitating a leaf at every stage, and the caterpillar is not a pest because it feeds only on wild buckthorn shrubs.
Other butterflies in the Whites and Sulphurs family
All Whites and Sulphurs (Pieridae) →
Whites and Sulphurs (Pieridae)Clouded Yellow (Colias croceus)
Whites and Sulphurs (Pieridae)Cabbage White (Pieris rapae)
Whites and Sulphurs (Pieridae)Green-veined White (Pieris napi)
Whites and Sulphurs (Pieridae)Clouded Sulphur (Colias philodice)
Whites and Sulphurs (Pieridae)Little Yellow (Eurema lisa)
Whites and Sulphurs (Pieridae)California Dogface (Zerene eurydice)Keep exploring
More whites and sulphurs butterflies
- Cloudless Sulphur (Phoebis sennae)
- Orange-tip (Anthocharis cardamines)
- Checkered White (Pontia protodice)
- Sleepy Orange (Eurema nicippe)
- Dappled White (Euchloe)
Butterfly guides