Picture: Caterpillar of Papilio machaon
Caterpillars are the larval stage of insects in the order Lepidoptera, which includes butterflies and moths. At this stage, their primary role is to eat and grow rapidly before transforming into their adult form. They hatch from eggs laid by adult insects, often on or near suitable food plants.
Physically, caterpillars have long, segmented bodies with a distinct head and multiple pairs of legs. In addition to three true legs near the front, they have fleshy “prolegs” along their abdomen that help them grip surfaces. Their bodies may be smooth, hairy, or covered in spines, depending on the species.
One of the most fascinating aspects of caterpillars is their feeding behavior. They are voracious eaters, consuming leaves, flowers, and sometimes even stems. This constant feeding allows them to store energy needed for their next stage. Some species are very selective about what they eat, relying on specific host plants.
Caterpillars grow by molting, a process known as ecdysis. As they outgrow their outer skin, they shed it several times, passing through stages called instars. With each molt, they increase in size and sometimes change in appearance.
When fully grown, a caterpillar enters the pupal stage, forming a chrysalis or cocoon. Inside, it undergoes a dramatic transformation called metamorphosis, reorganizing its body into that of a butterfly or moth. This stage can last from days to months, depending on the species and environment.
Caterpillars play an important role in ecosystems. They serve as a major food source for birds and other animals, while also influencing plant populations through their feeding. Despite their sometimes destructive reputation in gardens, they are essential for maintaining ecological balance and supporting biodiversity.
Picture: Woolly Bear Caterpillar
Different Types of Caterpillars
Monarch Caterpillar (Danaus plexippus)
One of the most recognisable caterpillars in North America, the Monarch is boldly striped in yellow, white, and black bands, serving as a vivid warning to predators of its toxicity. It feeds exclusively on milkweed plants, from which it sequesters toxic cardiac glycosides that make both the caterpillar and the adult butterfly unpalatable. It passes through five instars before forming its iconic jade-green chrysalis decorated with gold dots.
Tobacco Hornworm (Manduca sexta)
A large and impressive caterpillar, the Tobacco Hornworm is bright green with seven diagonal white stripes along its sides and a distinctive curved red horn at its rear. It belongs to the hawk moth family and is one of the most studied insects in biological research, used extensively in neuroscience and physiology laboratories. Despite its fearsome appearance, the horn is entirely harmless, and the caterpillar relies on its green colouration to blend into the foliage of tomato, tobacco, and related plants.
Swallowtail Caterpillar (Papilio polyxenes)
The Black Swallowtail caterpillar undergoes a remarkable transformation in appearance across its instars, beginning as a small, bird-dropping mimic before maturing into a striking green caterpillar banded with black and dotted with yellow spots. When threatened, it everts a bright orange, forked organ called an osmeterium from behind its head, releasing a foul-smelling chemical to deter predators. It feeds on plants in the carrot family, including dill, fennel, and parsley.
Woolly Bear Caterpillar (Pyrrharctia isabella)
Famous in North American folklore as a weather predictor, the Woolly Bear is a densely bristled caterpillar banded in rusty brown in the middle and black at both ends. It is the larval stage of the Isabella Tiger Moth and is remarkable for its ability to survive freezing temperatures by producing a natural antifreeze. It feeds on a wide variety of low-growing plants and grasses and can be found wandering in autumn as it searches for a place to overwinter.
Tomato Hornworm (Manduca quinquemaculata)
Closely related to the Tobacco Hornworm and often confused with it, the Tomato Hornworm is equally large and green but bears eight V-shaped white markings along its sides and a black horn rather than a red one. It is a significant agricultural pest of tomato, pepper, and eggplant crops, capable of defoliating plants rapidly due to its enormous appetite. Parasitic braconid wasps frequently lay their eggs inside it, and a caterpillar covered in white cocoons is best left undisturbed to allow the wasps to complete their life cycle.
Luna Moth Caterpillar (Actias luna)
The larva of one of North America’s most beautiful moths, the Luna Moth caterpillar is a plump, vivid green caterpillar with a yellow lateral stripe along each side, dotted with small orange or red spots. It feeds on a variety of deciduous trees including walnut, hickory, sweet gum, and birch, and passes through five instars before spinning a papery cocoon among leaf litter. When disturbed, it produces a clicking sound with its mandibles and regurgitates a bitter fluid as a defence against predators.
Painted Lady Caterpillar (Vanessa cardui)
The caterpillar of the world’s most widespread butterfly, the Painted Lady larva is a spiny, dark-coloured caterpillar with a black and yellow-mottled body covered in branching spines. It constructs a silk tent within the leaves of its host plant — most commonly thistles, mallows, and related species — and feeds within this shelter for protection. Its wide host range and adaptability have contributed to the success of the adult butterfly across nearly every continent.
Cecropia Moth Caterpillar (Hyalophora cecropia)
Among the most spectacular caterpillars in North America, the Cecropia Moth larva is a large, chunky, sea-green caterpillar adorned with rows of colourful tubercles — blue, yellow, and red knobbed projections that give it an almost jewelled appearance. It feeds on a wide variety of deciduous trees and shrubs, including cherry, apple, and willow. Despite its extraordinary appearance, it is entirely harmless and spends the winter as a large, tough silken cocoon attached to a tree branch.
Spicebush Swallowtail Caterpillar (Papilio troilus)
A master of disguise, the Spicebush Swallowtail caterpillar mimics a snake with startling effectiveness — its later instars display large, false eyespots on an inflated thorax, creating the convincing impression of a small green tree snake when viewed from the front. It lives within a folded leaf shelter on its host plant, spicebush or sassafras, venturing out only to feed. The osmeterium, when everted, adds to the snake-like illusion by resembling a flickering forked tongue.
Io Moth Caterpillar (Automeris io)
One of the most dangerous caterpillars to handle in North America, the Io Moth larva is a brilliant lime-green caterpillar covered in clusters of sharp, venomous spines that can cause intense pain, redness, and swelling upon contact. Early instars are reddish or orange before transitioning to green in later instars, and the caterpillars are often found in groups when young. They feed on a wide variety of plants including corn, clover, and various trees and shrubs.
Polyphemus Moth Caterpillar (Antheraea polyphemus)
A large, plump, bright green caterpillar with a series of yellow lines running along its sides and a reddish-brown head, the Polyphemus Moth larva is one of the largest caterpillars in North America. It feeds on a wide variety of deciduous trees including oak, maple, birch, and cherry, and produces a distinct clicking sound when disturbed. Before pupating, it spins a large, oval silken cocoon that is firmly attached to a branch or wrapped within a leaf.
White-Marked Tussock Moth Caterpillar (Orgyia leucostigma)
A visually striking and unmistakable caterpillar, the White-Marked Tussock Moth larva features four dense, white tufts of hair along its back, a bright red head, and long black pencil tufts projecting from its front and rear. The hairs can cause allergic skin reactions in sensitive individuals and should not be handled. It feeds on a wide variety of deciduous and coniferous trees and is considered a pest species when populations are high.
Saddleback Caterpillar (Acharia stimulea)
Named for the vivid green saddle-shaped marking on its brown back, the Saddleback caterpillar is one of the most recognisable and notorious stinging caterpillars in North America. Its body is covered in fleshy, spine-tipped lobes that deliver a venomous sting capable of causing intense pain, swelling, nausea, and in rare cases, more serious reactions. It feeds on a wide range of plants including corn, blueberry, and various ornamental species and is best observed rather than handled.
Gulf Fritillary Caterpillar (Agraulis vanillae)
A slender, orange-red caterpillar with black branching spines running the length of its body, the Gulf Fritillary larva is a specialist feeder on passionflower vines. The spines, while intimidating in appearance, are not venomous, and the caterpillar’s bold colouration serves as a warning that it has sequestered toxic compounds from its host plant. It is a common sight in gardens across the southern United States and is often used in butterfly gardening programmes.
Promethea Moth Caterpillar (Callosamia promethea)
A smooth, pale green caterpillar with four coral-red or yellow tubercles near its head and a single yellow tubercle near its tail, the Promethea Moth larva feeds on a variety of trees and shrubs including spicebush, sassafras, tulip tree, and wild cherry. Its smooth, waxy appearance helps it blend seamlessly into the foliage of its host plants. Before pupating, it spins a strong cocoon within a rolled leaf that remains attached to the twig throughout winter.
Hackberry Emperor Caterpillar (Asterocampa celtis)
A green caterpillar with a complex body shape — tapering at both ends, with a forked tail and two short horns on its head — the Hackberry Emperor larva is a highly specialised feeder on hackberry trees. Its body shape and green colouration make it exceptionally difficult to detect among hackberry leaves. It overwinters as a partially grown caterpillar in a shelter constructed from dead leaves, resuming feeding in spring before pupating.
Cabbage White Caterpillar (Pieris rapae)
A slender, velvety green caterpillar with a faint yellow stripe along its back and sides, the Cabbage White larva blends with extraordinary effectiveness into the foliage of its host plants. It is one of the most significant agricultural pests of cruciferous vegetables worldwide, feeding on cabbage, broccoli, kale, and related plants. Despite its plain appearance, it is a formidable pest capable of causing extensive damage to crops if populations are not controlled.
Eastern Tiger Swallowtail Caterpillar (Papilio glaucus)
In its early instars, the Eastern Tiger Swallowtail caterpillar mimics a bird dropping — dark brown and white — before transforming in later instars into a smooth green caterpillar with two large, intimidating false eyespots on its thorax. It feeds on a variety of deciduous trees including tulip poplar, wild cherry, and ash, and rests within a folded leaf shelter during the day. The osmeterium it everts when threatened produces a pungent, unpleasant smell that discourages many predators.
American Dagger Moth Caterpillar (Acronicta americana)
A densely hairy caterpillar dressed in pale yellow hairs with several long, black pencil tufts projecting from its back, the American Dagger Moth larva is a common sight on deciduous trees in eastern North America. While the hairs can cause skin irritation and should not be handled directly, the caterpillar is not venomous in the true sense. It feeds on a variety of hardwood trees including oak, maple, hickory, and elm before descending to pupate in leaf litter.
Viceroy Caterpillar (Limenitis archippus)
A remarkable mimic of a bird dropping in its early instars, the Viceroy caterpillar is mottled brown and white with a pair of small, thorn-like tubercles behind its head. It feeds exclusively on willow, poplar, and cottonwood trees, and overwinters as a partially grown larva inside a rolled leaf tube it constructs and fastens to a twig. The adult Viceroy butterfly famously mimics the Monarch, but the caterpillar relies entirely on camouflage rather than chemical defence.
Question Mark Caterpillar (Polygonia interrogationis)
A spiny black caterpillar with orange markings and branching spines covering its body, the Question Mark larva feeds primarily on elm, hackberry, and hops. Its dark colouration and spiny texture make it conspicuous but difficult for predators to handle comfortably. It is a solitary feeder in later instars and pupates hanging from a branch in a chrysalis that bears a silver or gold mark — the punctuation that gives both the caterpillar and its adult butterfly their common name.
Hickory Horned Devil (Citheronia regalis)
Arguably the most spectacular caterpillar in North America, the Hickory Horned Devil is a massive, blue-green larva adorned with long, curved orange and black horns behind its head and smaller spines along its body. Despite its terrifying appearance — it can reach up to 15 cm in length — it is completely harmless and incapable of stinging or biting effectively. It feeds on walnut, hickory, sweet gum, and persimmon trees before descending to burrow into the soil to pupate, emerging as the Royal Walnut Moth.
Variegated Fritillary Caterpillar (Euptoieta claudia)
A white caterpillar with bold black stripes running lengthwise along its body, accented with orange at the base of each branching spine, the Variegated Fritillary larva feeds on a wide variety of host plants including passionflower, violets, stonecrop, and mayapple. Its catholic diet makes it one of the more adaptable fritillary larvae. It produces multiple broods per year in warmer regions and is found across a broad geographic range from North America to South America.
Pipevine Swallowtail Caterpillar (Battus philenor)
A strikingly dark caterpillar ranging from deep reddish-brown to near-black, adorned with rows of fleshy orange tubercles along its back, the Pipevine Swallowtail larva feeds exclusively on pipevine plants. It sequesters toxic aristolochic acids from its host plant, rendering both the caterpillar and adult butterfly highly toxic to vertebrate predators. Several other butterfly species, including the Spicebush and Black Swallowtail, mimic the adult Pipevine Swallowtail’s appearance in a classic example of Batesian mimicry.
Zebra Longwing Caterpillar (Heliconius charithonia)
A white caterpillar covered in rows of black spines and black spots, the Zebra Longwing larva feeds exclusively on passionflower vines and is capable of tolerating the plant’s defensive cyanogenic compounds. Adult females of this species lay their eggs with precision, often stacking them in clusters, and the caterpillars may feed gregariously in early instars. Found throughout the Caribbean, Central America, and the southern United States, it is the state butterfly of Florida in its adult form.
Red Admiral Caterpillar (Vanessa atalanta)
A variable caterpillar ranging from dark grey or black to pale brown, covered in branching spines, the Red Admiral larva constructs a distinctive shelter by folding and silking together leaves of its host plant, most commonly stinging nettle. It feeds within this shelter, emerging to feed on the surrounding foliage before retreating. The adult butterfly is one of the most widespread and instantly recognisable in the Northern Hemisphere, and the caterpillar’s nettle dependence makes it a key species in nettle-rich habitats.
Common Buckeye Caterpillar (Junonia coenia)
A dark, almost black caterpillar with orange stripes along its sides and rows of iridescent blue-based branching spines, the Common Buckeye larva feeds on a variety of low-growing plants including plantain, snapdragon, and toadflax. Its spiny appearance serves as a deterrent to many predators, and it is a relatively fast-growing species, completing its larval stage in just a few weeks under warm conditions. The adult butterfly is famous for the striking eyespots on its wings.
Mourning Cloak Caterpillar (Nymphalis antiopa)
A striking, gregarious caterpillar in its early instars, the Mourning Cloak larva is black with rows of orange-red spots along its back and covered in numerous black branching spines. Young caterpillars feed in large, conspicuous groups that may deter some predators through sheer numbers, before dispersing to feed individually in later instars. They feed on willow, elm, poplar, and hackberry, and the adult butterfly is one of the longest-lived in North America, overwintering as an adult.
Giant Leopard Moth Caterpillar (Hypercompe scribonia)
A densely bristled, jet-black caterpillar with bright red bands visible between its body segments when it curls into a defensive ball, the Giant Leopard Moth larva is one of the most dramatic-looking woolly caterpillars in North America. Despite its striking appearance, the bristles are not venomous, though they may cause mild skin irritation in sensitive individuals. It feeds on a wide variety of plants and overwinters as a larva, completing its development in spring.
Spiny Elm Caterpillar (Nymphalis antiopa larva form)
The early larval form of the Mourning Cloak butterfly, the Spiny Elm caterpillar is sometimes treated as a distinct common form due to its conspicuous appearance and elm-feeding habits. It is black with red spots and long black spines, feeding gregariously on elm and willow in tight, writhing clusters that can defoliate entire branches. The group feeding behaviour is thought to provide a thermal advantage as well as collective deterrence against predators.
Banded Woollybear Caterpillar (Pyrrharctia isabella)
While sharing its scientific name with the Woolly Bear, the Banded Woollybear is the same species described at different seasonal stages or geographic variants, distinguished by varying proportions of its rusty-brown and black banding. Folklore holds that a wider brown band predicts a milder winter, though scientific evidence does not support this claim — the band width reflects age and local conditions rather than weather forecasting ability. It is widely beloved as a seasonal symbol of autumn in North America.
Cloudless Sulphur Caterpillar (Phoebis sennae)
A caterpillar that varies considerably in colour — ranging from yellow-green to bright yellow with a lateral stripe and blue or black spots — the Cloudless Sulphur larva feeds exclusively on senna and related legumes. The colour variation is thought to be related to diet, with caterpillars feeding on flowers appearing more yellow and those feeding on leaves appearing greener. It is a strong migratory butterfly as an adult, and its caterpillar is commonly encountered in gardens planted with senna species.
Harvester Caterpillar (Feniseca tarquinius)
The only carnivorous butterfly caterpillar in North America, the Harvester larva feeds exclusively on woolly aphids rather than plant material — a unique ecological role among butterflies. It is a small, slug-like caterpillar that conceals itself among aphid colonies, sometimes camouflaging itself with the waxy secretions of its prey. This specialised diet means it is restricted to habitats where alder, beech, or witch hazel grow in association with woolly aphid colonies.
Silver-Spotted Skipper Caterpillar (Epargyreus clarus)
A distinctive caterpillar with a large, swollen green body, a constricted neck, and a prominent, reddish-brown head adorned with two bold orange eyespots that give it a startling face-like appearance. It constructs a leaf shelter by cutting and folding leaves of its host plant — most commonly black locust and related legumes — and rests within this retreat during the day, emerging at night to feed. The false eyespots are thought to deter or startle potential predators approaching from the front.
Anise Swallowtail Caterpillar (Papilio zelicaon)
Found across western North America, the Anise Swallowtail caterpillar is a striking green larva banded with black stripes and dotted with bright orange spots, closely resembling the Black Swallowtail caterpillar of the east. It feeds on plants in the carrot family, including fennel, anise, and wild parsnip, and like other swallowtail larvae, everts a brightly coloured osmeterium when disturbed. It is a common butterfly garden visitor in the western United States wherever its host plants are grown.
White Admiral Caterpillar (Limenitis arthemis arthemis)
Closely related to the Viceroy, the White Admiral caterpillar is similarly cryptic in its early instars, mimicking a bird dropping with mottled brown and white markings and a pair of small tubercles behind the head. It feeds on birch, willow, and cherry, and overwinters in a carefully constructed leaf roll called a hibernaculum. The adult butterfly’s bold white band on a dark wing is one of the most striking patterns in North American butterfly fauna.
Checkered White Caterpillar (Pontia protodice)
A pale green caterpillar with yellow and purple longitudinal stripes, the Checkered White larva feeds on plants in the mustard family and is found across much of North America, particularly in disturbed, open habitats. It is a cryptic species that blends well with the foliage and flowers of its host plants, making it difficult to detect in the field. Multiple broods are produced annually in warmer regions, and populations fluctuate considerably from year to year.
Milkweed Tussock Moth Caterpillar (Euchaetes egle)
A gregarious caterpillar in its early instars, the Milkweed Tussock Moth larva is covered in dense tufts of black, white, and orange hairs that make it one of the most visually dramatic milkweed feeders. Like the Monarch, it sequesters toxic cardiac glycosides from milkweed, making it unpalatable to most predators. Young caterpillars feed in tight clusters, skeletonising milkweed leaves, while older caterpillars disperse to feed more individually.
Eight-Spotted Forester Caterpillar (Alypia octomaculata)
A pale caterpillar with bold black and orange banding and a smooth body texture, the Eight-Spotted Forester larva feeds on wild grape and Virginia creeper. The striking banding is thought to serve as a warning to predators, as the caterpillar may sequester defensive compounds from its host plant. The adult moth, with its bold black wings spotted in white and yellow, is one of the most attractive day-flying moths in eastern North America.
Banded Sphinx Moth Caterpillar (Darapsa myron)
A large, smooth, green caterpillar with a curved horn at its rear and oblique white or yellow stripes along its sides, the Banded Sphinx Moth larva feeds on grape and Virginia creeper. As with other hawk moth larvae, it pupates in the soil rather than spinning a cocoon. Late-instar caterpillars may turn reddish-purple or brown before pupating — a colour shift that helps camouflage them against leaf litter as they wander in search of a pupation site.
American Lady Caterpillar (Vanessa virginiensis)
A dark caterpillar with yellow transverse bands and black branching spines, the American Lady larva feeds primarily on everlastings and pussytoes in the daisy family. Like the Painted Lady, it constructs a silk-reinforced leaf shelter and feeds within it for protection. The adult butterfly features two large eyespots on the underside of its hindwings — a key distinguishing feature from the similar Painted Lady, which has four smaller eyespots.
Giant Silk Moth Caterpillar (Saturnia pyri)
The largest moth caterpillar in Europe, the Giant Peacock Moth larva is a massive, fleshy green caterpillar studded with blue and yellow tubercles tipped with black bristles, reaching lengths of up to 10 cm in its final instar. It feeds on a variety of fruit and deciduous trees including pear, cherry, and walnut, and spins a remarkably sturdy, flask-shaped silken cocoon before pupating. The adult, with its enormous wingspan and striking eyespots, is the largest moth species found in Europe.
Puss Moth Caterpillar (Cerura vinula)
One of the most extraordinary caterpillars in the world, the Puss Moth larva is bright green with a dark saddle marking and a distinctive face featuring two false eyespots that give it a startling, almost comical expression. When threatened, it raises its head and tail simultaneously, everts a pink whip-like filament from its forked tail, and may squirt formic acid from a gland near its head — a multi-layered defence system that deters even experienced predators. It feeds on willow and poplar throughout Europe.
Elephant Hawk-Moth Caterpillar (Deilephila elpenor)
Named for the trunk-like shape of its head end when retracted, the Elephant Hawk-Moth caterpillar is a large, dramatic larva that comes in two colour forms — green and a much more common dark brown — both bearing four large, vivid false eyespots on the thorax. When threatened, it withdraws its head into its thorax, causing the eyespots to bulge and expand, creating a convincing impression of a large snake or toad. It feeds primarily on willowherb, fuchsia, and bedstraw across Europe and Asia.
Cinnabar Moth Caterpillar (Tyria jacobaeae)
One of the most visually striking caterpillars in Europe, the Cinnabar Moth larva is banded in bold orange and black — a classic aposematic warning that it is toxic and unpalatable. It feeds gregariously and almost exclusively on ragwort, from which it sequesters pyrrolizidine alkaloids that make it poisonous to most vertebrate predators. The caterpillars can completely defoliate ragwort plants, and their gregarious feeding and conspicuous colouration make them highly visible to human observers.
Garden Tiger Moth Caterpillar (Arctia caja)
Commonly known as the Woolly Bear in the United Kingdom, the Garden Tiger Moth larva is a large, densely hairy caterpillar covered in long, dark brown to black hairs on its back and reddish-brown hairs on its sides. It feeds on a wide variety of low-growing plants including dock, nettle, and dandelion, and can often be found wandering in spring as it searches for a pupation site. Handling the hairs can cause skin irritation, and the caterpillar’s striking appearance advertises its unpalatability.
Six-Spot Burnet Moth Caterpillar (Zygaena filipendulae)
A plump, pale yellowish-green caterpillar with rows of black spots, the Six-Spot Burnet Moth larva feeds on bird’s-foot trefoil and other vetches in grassland habitats across Europe. It produces and stores hydrogen cyanide in its tissues — both synthesised internally and acquired from its host plant — making it highly toxic to predators. The caterpillar spins a distinctive papery, spindle-shaped cocoon attached to a grass stem before pupating.
Small Tortoiseshell Caterpillar (Aglais urticae)
A gregarious, spiny caterpillar that feeds almost exclusively on common stinging nettle, the Small Tortoiseshell larva is one of the most familiar caterpillars in European gardens and countryside. It is black with broken yellow lateral bands and covered in branching yellow spines, feeding in large, dense groups when young before gradually dispersing in later instars. The adult butterfly is one of the most common and beloved in the United Kingdom, frequently overwintering in garden sheds and outbuildings.
Peacock Butterfly Caterpillar (Aglais io)
Entirely jet black with white speckling and rows of branching black spines, the Peacock Butterfly caterpillar is unmistakable among British and European butterfly larvae. Like the Small Tortoiseshell, it feeds gregariously on stinging nettles in dense silken webs when young, becoming more solitary in later instars. The adult Peacock butterfly is one of Europe’s most iconic species, famous for the vivid blue eyespots on its wings that it displays suddenly to startle potential predators.
Comma Butterfly Caterpillar (Polygonia c-album)
A caterpillar that performs a remarkable disguise — its back is dark brown to black with an irregular white patch resembling a bird dropping, while its underside is orange-brown. This striking camouflage in its later instars helps it avoid detection while resting on the upper surfaces of leaves. It feeds on stinging nettle, hop, and elm in Europe and Asia, and the adult butterfly’s ragged wing outline helps it blend into dead leaf litter when overwintering.
Brimstone Butterfly Caterpillar (Gonepteryx rhamni)
A slender, smooth, pale green caterpillar with a faint white lateral stripe, the Brimstone larva is superbly camouflaged along the midrib of its host plant’s leaves — buckthorn and alder buckthorn. It lies along leaf veins in a characteristic resting posture that makes it extraordinarily difficult to detect even upon close inspection. The adult male is a vivid sulphur yellow and is thought to be the origin of the word “butterfly” in the English language.
Orange-tip Butterfly Caterpillar (Anthocharis cardamines)
A beautifully camouflaged blue-green caterpillar with a white lateral stripe, the Orange-tip larva feeds on the seed pods of lady’s smock, garlic mustard, and related cruciferous plants. It is a cannibalistic species — caterpillars will consume each other if they meet on the same plant, which explains why females lay only one egg per plant. The adult male’s vivid orange wingtips make it one of the most recognisable signs of spring in European woodlands and hedgerows.
Wood White Butterfly Caterpillar (Leptidea sinapis)
A slender, elongated green caterpillar with a darker green dorsal stripe and a yellowish lateral stripe, the Wood White larva feeds on meadow vetchling, bitter vetch, and related legumes in woodland clearings and rides across Europe. Its narrow, grass-like body is exceptionally cryptic among the foliage of its host plants. The adult is the most delicate of European white butterflies, with weak, fluttery flight and beautifully rounded wings.
Purple Emperor Caterpillar (Apatura iris)
One of the most extraordinary caterpillars in Britain, the Purple Emperor larva bears a remarkable resemblance to a grey-green slug at rest, with two prominent green horns on its head and a tapering tail that creates a leaf-like silhouette. It feeds exclusively on goat willow and grey willow, resting along the midrib of leaves in perfect camouflage. It overwinters as a small caterpillar on a twig, resuming feeding in spring, and the adult male is one of Britain’s most spectacular insects with its iridescent purple sheen.
White Letter Hairstreak Caterpillar (Satyrium w-album)
A flat, woodlouse-shaped green caterpillar with diagonal pale stripes, the White Letter Hairstreak larva feeds on the flowers and developing seeds of elm trees, making it particularly vulnerable to the decline of elms due to Dutch elm disease. Its flattened shape and green colouration provide effective camouflage among the elm’s textured foliage. The adult butterfly is a small, brown butterfly with a distinctive white W-shaped line on the underside of its hindwing.
Brown Hairstreak Caterpillar (Thecla betulae)
A plump, pale green caterpillar with diagonal yellow stripes and a velvety texture, the Brown Hairstreak larva feeds on blackthorn and occasionally other prunus species. It overwinters as an egg — one of the last butterfly eggs to hatch in spring — and feeds nocturnally in later instars, spending the day resting cryptically on a leaf. The adult female is one of Britain’s most beautiful butterflies, while the male is rarely seen except at the tops of ash trees where the adults congregate.
Green Hairstreak Caterpillar (Callophrys rubi)
A flat, woodlouse-shaped, bright green caterpillar with yellow diagonal stripes, the Green Hairstreak larva feeds on a remarkably wide range of host plants including gorse, broom, rock-rose, and bilberry, making it one of the more ecologically flexible hairstreak species. Its green, slug-like body provides excellent camouflage against the foliage of its varied host plants. The adult butterfly is Britain’s only entirely green butterfly, with iridescent green undersides and cryptic brown upperwings.
Chalkhill Blue Caterpillar (Polyommatus coridon)
A bright green caterpillar with yellow stripes along its back and sides, the Chalkhill Blue larva feeds on horseshoe vetch in chalk and limestone grassland habitats. Like many blue butterfly larvae, it has a honey gland that secretes a sugary liquid attractive to ants, which tend and protect the caterpillar in exchange. This mutualistic relationship with ants provides the caterpillar with significant protection from parasitoids and predators.
Adonis Blue Caterpillar (Polyommatus bellargus)
Almost identical in appearance to the Chalkhill Blue caterpillar, the Adonis Blue larva is a bright green caterpillar with yellow stripes that feeds exclusively on horseshoe vetch in very short chalk grassland. It too is attended by ants, which are attracted to the secretions of its dorsal nectary organ and lateral organs. The adult male’s vivid electric-blue wings are among the most brilliant of any British butterfly, rivalled in intensity only by a few tropical species.
Duke of Burgundy Caterpillar (Hamearis lucina)
A small, pale brown, hairy caterpillar, the Duke of Burgundy larva feeds on cowslip and primrose in woodland clearings and chalk downland. Despite the adult butterfly’s common name suggesting grandeur, the caterpillar is a modest, inconspicuous larva that blends effectively with its host plant’s leaves. It is the sole representative of the Riodinidae family — the metalmarks — in Britain and Europe, and the adult is one of Britain’s most localised and declining butterfly species.
Marbled White Butterfly Caterpillar (Melanargia galathea)
A pale, straw-coloured caterpillar with a dark dorsal stripe, the Marbled White larva feeds on fescue and other fine-leaved grasses in chalk and limestone grassland. Unusually for a butterfly larva, it feeds nocturnally and hides at the base of grass tussocks during the day. It overwinters as a tiny caterpillar immediately after hatching from the egg, resuming feeding in early spring, and the adult’s striking black-and-white chequered wings make it one of Europe’s most recognisable grassland butterflies.
Grayling Butterfly Caterpillar (Hipparchia semele)
A pale, straw-coloured caterpillar with a series of darker longitudinal stripes, the Grayling larva feeds on fine-leaved grasses including fescues, bents, and bristle grasses in dry, open habitats such as heathland, coastal cliffs, and sand dunes. Like the Marbled White, it feeds nocturnally and conceals itself at the base of vegetation during the day. The adult butterfly is a master of camouflage, pressing itself against the ground and tilting toward the sun to eliminate its shadow.
Large Heath Caterpillar (Coenonympha tullia)
A pale green caterpillar with a white lateral stripe and a forked tail, the Large Heath larva feeds on white beak-sedge and cotton-grass in boggy moorland habitats. It is a slow-developing species that may take two years to complete its larval stage in colder parts of its range. The adult butterfly is one of Britain’s most geographically variable species, with distinct regional forms recognised across Scotland, northern England, and Wales.
Scotch Argus Caterpillar (Erebia aethiops)
A pale, straw-coloured caterpillar with dark longitudinal stripes, the Scotch Argus larva feeds on purple moor-grass and blue moor-grass in upland grasslands and woodland clearings. It overwinters as a small larva, feeding very slowly through the cold months, and completes its development in late spring. The adult is a dark, velvety-brown butterfly with red-ringed eyespots, found only in Scotland and a handful of sites in northern England in the British Isles.
Mountain Ringlet Caterpillar (Erebia epiphron)
Britain’s only true alpine butterfly, the Mountain Ringlet larva is a pale green caterpillar with darker stripes that feeds on mat-grass in upland habitats above 500 metres. Its development is extremely slow, taking up to two years in harsh mountain conditions, and the caterpillar is highly adapted to cold, wet, and variable mountain weather. The adult butterfly flies only briefly in warm, sunny conditions and disappears rapidly when clouds obscure the sun.
Large Blue Caterpillar (Phengaris arion)
One of the most extraordinary life cycles of any insect in the world, the Large Blue caterpillar initially feeds on wild thyme flowers before dropping to the ground and secreting chemicals that deceive Myrmica ants into carrying it into their nest. Once inside, it spends the remainder of its larval stage feeding on ant grubs, mimicking the sounds and chemical signals of the queen ant to avoid attack. It is entirely dependent on a specific species of Myrmica ant for its survival and was extinct in Britain before being successfully reintroduced.
Magpie Moth Caterpillar (Abraxas grossulariata)
A cream-coloured caterpillar with black spots and an orange lateral stripe, the Magpie Moth larva feeds on currant, gooseberry, hawthorn, and sloe, and was once a significant pest of soft-fruit gardens in Britain. Its bold colouration is aposematic, warning predators that it is unpalatable. The adult moth is similarly striking, with white wings patterned in black spots and orange-yellow banding, making it one of the most recognisable moths in European gardens.
Garden Tiger Moth Caterpillar (Arctia caja) — European form
In its European form, the Garden Tiger Moth larva is particularly associated with a wide range of garden plants and weeds and is one of the most commonly encountered hairy caterpillars across the continent. Its long, dark hairs contain histamine-like compounds that can cause skin irritation, and birds that attempt to eat it typically reject it quickly due to its foul taste. Despite declining significantly across northern Europe in recent decades — possibly linked to climate change — it remains a widespread and familiar species.
Buff-tip Moth Caterpillar (Phalera bucephala)
A gregarious, vividly coloured caterpillar banded in yellow and black with long, pale hairs, the Buff-tip Moth larva feeds communally on the leaves of oak, lime, hazel, and willow, sometimes causing spectacular defoliation of individual branches. Young caterpillars feed side by side in tight rows, moving across leaves in synchrony, while older caterpillars disperse to feed more independently. The adult moth is a masterful camouflage artist, resembling a broken silver birch twig when at rest.
Privet Hawk-Moth Caterpillar (Sphinx ligustri)
A large, smooth, bright green caterpillar with seven purple and white diagonal stripes along each side and a curved black horn at its rear, the Privet Hawk-Moth larva is one of the largest caterpillars found in the British Isles. It feeds on privet, ash, and lilac, and in its final instar turns brownish-purple before burrowing into the soil to pupate. Despite its impressive size, it is cryptically camouflaged among the leaves of its host plants and is rarely found except by dedicated searching.
Eyed Hawk-Moth Caterpillar (Smerinthus ocellata)
A large green caterpillar with seven oblique white or yellow stripes along its sides and a bluish horn, the Eyed Hawk-Moth larva feeds on willow, apple, and poplar. Like other hawk moth caterpillars, it is well camouflaged against the foliage of its host plant and pupates underground. When the adult moth is threatened, it reveals a pair of vivid blue and black eyespots on its hindwings with a sudden flash — one of the most startling defensive displays of any European moth.
Poplar Hawk-Moth Caterpillar (Laothoe populi)
A stout, green caterpillar with yellow oblique stripes along its sides and a distinctive yellow horn at its tail, the Poplar Hawk-Moth larva feeds on poplar, willow, and aspen throughout Europe. In its final instar, the caterpillar turns yellow-green or pinkish before descending to pupate shallowly in the soil. The adult moth has an unusual resting posture — its hindwings are held forward of the forewings — giving it a distinctively crumpled, leaf-like silhouette.
Old World Swallowtail Caterpillar (Papilio machaon)
The caterpillar of one of Europe’s largest and most celebrated butterflies, the Old World Swallowtail larva is a striking green caterpillar with black bands and bright orange spots, closely resembling the Black Swallowtail of North America. It feeds on wild carrot, milk parsley, and related umbellifers, and like other swallowtail larvae, produces an osmeterium when disturbed. In Britain, it is restricted to the Norfolk Broads where it feeds exclusively on milk parsley, making it one of the country’s rarest butterfly larvae.
Lobster Moth Caterpillar (Stauropus fagi)
Perhaps the most bizarre-looking caterpillar in the British Isles, the Lobster Moth larva has an extraordinary body shape — an enlarged, swollen thorax, elongated legs on its front segments, and a tail that curls dramatically upward and over its back, resembling the abdomen of a lobster. When threatened, it raises its head, arches its tail, and may exude formic acid from a gland on its thorax, creating a dramatic and effective multi-sensory deterrent. It feeds on beech, hazel, oak, and birch in woodland habitats.
Figure of Eight Moth Caterpillar (Diloba caeruleocephala)
A pale grey or blue-grey caterpillar with yellow and black markings and a distinctive blue-grey head, the Figure of Eight Moth larva is a communal feeder in its early instars, feeding on hawthorn, blackthorn, and apple in hedgerows and orchards. Its bold patterning serves as an aposematic warning, though the caterpillar is not significantly toxic. The adult moth gets its name from a figure-of-eight marking on its forewing and is a common autumn species across much of Europe.
Peach Blossom Moth Caterpillar (Thyatira batis)
A brown caterpillar with white-edged humps along its back and a cryptic resting posture that allows it to blend seamlessly with dead leaves and woody debris, the Peach Blossom Moth larva feeds on bramble and raspberry in hedgerows and woodland edges. The humps on its back break up its outline and help it avoid detection against the dappled background of the woodland floor. The adult moth’s forewings are decorated with pink and white spots that resemble apple blossom.
Merveille du Jour Moth Caterpillar (Griposia aprilina)
A grey-green caterpillar with dark and pale markings, the Merveille du Jour Moth larva feeds on oak, consuming the developing flowers and leaves in spring before completing its development in early summer. Its colouration provides excellent camouflage against lichen-covered oak bark, where it may rest during the day. The adult moth is considered one of the most beautiful in Britain, its wings patterned in intricate shades of green, black, and white that perfectly mimic lichen on bark.
Lappet Moth Caterpillar (Gastropacha quercifolia)
A large, flat, grey-brown caterpillar with distinctive blue-grey lateral lobes along each side that press against the bark of its resting surface, eliminating its shadow and making it virtually invisible against the bark of its host tree. It feeds on blackthorn, hawthorn, and apple and is found across Europe and into Asia. In its resting posture on a bark surface, with lobes spread and hairs matted against the substrate, it represents one of the most sophisticated bark-mimics among European caterpillars.
Oak Processionary Moth Caterpillar (Thaumetopoea processionea)
A highly social caterpillar that travels in long, nose-to-tail processions — sometimes involving thousands of individuals — to reach feeding sites on oak trees, the Oak Processionary Moth larva is a significant pest and public health concern in parts of Europe. Its body is covered in thousands of microscopic barbed hairs containing the protein thaumetopoein, which can cause severe skin rashes, eye irritation, and respiratory problems in humans and animals. Nests should never be approached or disturbed without specialist protective equipment.
Pine Processionary Moth Caterpillar (Thaumetopoea pityocampa)
Similar in behaviour to the Oak Processionary, the Pine Processionary Moth larva forms long processions and builds conspicuous silk communal nests in pine and cedar trees across southern Europe and the Mediterranean. The caterpillars move in processions at night to feed on pine needles, returning to their nest before dawn, and the procession may contain hundreds of individuals following each other in a continuous silken thread. Like its oak-feeding relative, its urticating hairs pose a serious health risk to humans and animals.
Mullein Moth Caterpillar (Cucullia verbasci)
A spectacularly beautiful caterpillar dressed in white with bold spots of black and yellow arranged in a distinctive pattern along its body, the Mullein Moth larva feeds openly on the flowers and leaves of mullein, figwort, and buddleia during the day. Unlike most caterpillars, it makes no effort to hide, relying instead on its bold aposematic colouration to deter predators. It pupates underground in a tough, earthen cocoon that may persist in the soil for several years before the adult moth emerges.
Death’s Head Hawk-Moth Caterpillar (Acherontia atropos)
One of the largest caterpillars found in the British Isles and Europe, the Death’s Head Hawk-Moth larva is a massive, smooth caterpillar that occurs in two colour forms — green with purple and white diagonal stripes, or yellow with similar striping — both bearing a curved, ridged horn at the tail. It feeds on potato foliage, woody nightshade, and related plants, and like all hawk moth larvae, pupates underground in a firm earthen chamber. The adult moth is famous for the skull-like pattern on its thorax and its ability to squeak when disturbed.