What Predators Eat Butterflies

In this guide

1. What eats butterflies?
2. Predators at each stage of the life cycle
3. Birds: the main predators of adult butterflies
4. Spiders, wasps, mantises and other invertebrates
5. Parasitoids and disease: the hidden killers
6. How butterflies protect themselves from predators
7. Did you know?
8. Frequently asked questions

What eats butterflies?

Butterflies are eaten by an enormous range of animals: birds are the main predators of adults, while spiders, praying mantises, dragonflies, robber flies, assassin bugs, wasps, ants, lizards, frogs, toads, mice and even monkeys take butterflies whenever they can catch them. The eggs, caterpillars and chrysalises suffer most, because they cannot fly away, and on top of the predators they are attacked by parasitoid wasps and flies that lay their eggs inside them.

The scale of the loss is hard to overstate. A female may lay several hundred eggs, yet field studies of species such as the monarch find that usually fewer than one in ten, and often fewer than one in twenty, survives to fly. The rest are eaten, parasitised, killed by disease or lost to weather, and most of the killing happens in the first two weeks of life, when the insect is a small egg or a soft, slow caterpillar on an exposed leaf.

The older version of this page described butterflies as sitting at the bottom of the food chain. They are better described as primary consumers near its base: the caterpillars turn leaves into protein, and that protein feeds the nestlings of most songbirds, the larvae of countless wasps, and the spiders and lizards a garden depends on. Losing butterflies would mean losing much of what eats them.

Predators at each stage of the life cycle

Each stage of the butterfly life cycle has its own set of enemies.

Eggs

Butterfly eggs are eaten by ants, ladybird beetles and their larvae, lacewing larvae, earwigs, mites and predatory bugs, and they are parasitised by minute wasps of the genus Trichogramma that develop inside the egg and emerge in place of the caterpillar. Because a single egg is so small, a foraging ant can clear a whole cluster in minutes, and egg loss alone can remove half of a brood.

Caterpillar

This is the stage on which almost everything feeds. Paper wasps and yellowjackets hunt caterpillars to chew into paste for their own larvae, stink bugs and assassin bugs spear them, ground beetles and spiders hunt them at night, and birds collect them by the thousand to feed their chicks. Parasitoid flies and wasps add a second wave of mortality from the inside. A caterpillar that is found is very rarely left alone, which is why so many hide by day, feed at night or drop from the leaf on a silk thread when disturbed.

Chrysalis

A chrysalis cannot move, so it relies entirely on disguise. Those that are found are opened by birds, mice and shrews, drained by wasps and pierced by ichneumonid wasps with long ovipositors. Many caterpillars pupate well away from the host plant, in leaf litter or under bark, precisely because the plant is the first place a predator searches.

Adult butterfly

An adult is the hardest stage to catch and, for a predator, the least rewarding, since the wings are inedible scales and membrane. Even so, birds snap butterflies out of the air and off flowers, crab spiders ambush them inside blossoms, orb-weavers net them, mantises seize them, dragonflies and robber flies take them in flight, and lizards and frogs catch ground-loving species such as the common buckeye when they land low. A wing with a neat V-shaped notch is the signature of a bird that struck and missed the body.

Birds: the main predators of adult butterflies

Birds are the predators that have shaped butterfly evolution more than any other. Flycatchers, swallows, warblers, jays, sparrows and orioles all take adults, and the caterpillars of butterflies and moths are the single most important food of nestling songbirds: a pair of chickadees can deliver several thousand caterpillars to one brood. Because birds hunt by sight and learn quickly, a jay that has vomited once after swallowing a pipevine swallowtail avoids that pattern for life, and they are the reason butterflies are so often camouflaged, so often marked with eyespots, and so often coloured to advertise that they taste bad.

The clearest demonstration is at the monarch's winter roosts in the mountains of central Mexico, where tens of millions of butterflies hang in the fir trees. Two birds, the black-backed oriole and the black-headed grosbeak, have learned to eat them despite their milkweed toxins, the oriole by slitting the abdomen and eating only the insides and the grosbeak by tolerating the poison, and together they can kill more than a million monarchs in a single winter. A small black-eared mouse joins them on the forest floor at night, eating the butterflies that have fallen. Predation on this scale is one reason the butterfly migration concentrates so many individuals in so few places.

Spiders, wasps, mantises and other invertebrates

Most of the animals that eat butterflies are other arthropods. Crab spiders sit inside flowers, matching the petals, and grab the butterfly by the head as it feeds; an orb-weaver's web catches anything that blunders into it, though loose scales let many butterflies slip free. Jumping spiders stalk small blues and skippers on leaves, and wolf spiders take resting butterflies at night.

Praying mantises wait on flowers and stems and can take a butterfly as large as a swallowtail. Dragonflies and robber flies are aerial hunters that intercept butterflies in flight, and assassin bugs and ambush bugs spear adults that land beside them. Social wasps are the great hunters of caterpillars, but hornets and yellowjackets will also cut the wings from a living butterfly and carry the body off, and ants, which cannot catch a healthy adult, kill vast numbers of eggs, larvae and freshly emerged adults whose wings have not yet hardened.

Not every insect relationship is hostile. Caterpillars of many blues and hairstreaks in the gossamer-winged family secrete a sugary fluid that attracts ants, and the ants then guard them against wasps and parasitoids in return.

Parasitoids and disease: the hidden killers

The most important enemies of caterpillars are not predators at all but parasitoids, insects whose larvae develop inside a living host and kill it as they finish. Tachinid flies glue eggs to a caterpillar's skin or to the leaf it is eating; the maggot burrows in and feeds on the host, which usually dies as a chrysalis. Braconid wasps lay dozens of eggs in one caterpillar, and their larvae chew their way out to spin tiny white cocoons on its back. Ichneumonid and chalcid wasps attack the chrysalis. In many studies parasitoids account for more caterpillar deaths than birds, wasps and spiders combined, and rearing wild-collected caterpillars often produces more flies than butterflies.

Disease does the rest. A protozoan parasite, Ophryocystis elektroscirrha, is spread by infected monarch females onto their eggs and weakens or kills the adults that develop from them; viral and bacterial infections turn caterpillars into dark, liquefying corpses that hang from the leaf; and fungal outbreaks can wipe out chrysalises in a wet autumn. Together these unseen killers, rather than the visible bird or spider, decide how many butterflies a summer produces.

How butterflies protect themselves from predators

Butterflies survive this pressure with a layered set of defences, most of them aimed at the eyes of birds.

Camouflage. The commonest defence is not being seen. The closed wings of a question mark or a comma are dead-leaf brown with a leaf's outline, a mourning cloak at rest is a piece of bark, and the glasswing butterfly has done away with most of its scales so that a bird sees the leaf behind it. Caterpillars are green like leaves, striped like grass, or disguised as bird droppings, and a chrysalis mimics a leaf, a twig or a stone.

Eyespots and false heads. Large eyespots like those of the common buckeye startle a bird into hesitating for the half-second the butterfly needs to escape, while the small spots and tails at the hindwing edge of hairstreaks and blues create a false head that draws the strike to the wrong end. A notched hindwing is cheap; a pierced body is fatal. The guide to butterflies with eyes on their wings explains both tricks.

Toxins and warning colours. The monarch caterpillar stores cardenolides from milkweed, so that a bird which swallows the adult vomits within minutes and remembers the orange-and-black pattern for life. The pipevine swallowtail does the same with aristolochic acids from its host vines, and the queen, the zebra longwing and many tropical brush-footed butterflies are protected in similar ways. Bold, contrasting butterfly colours are the advertisement; the strategy is called aposematism.

Mimicry. Once birds avoid a toxic pattern, other species copy it. The viceroy is the classic example. For a century it was described, as it was in the older version of this page, as a harmless mimic of the monarch, but feeding trials with birds showed that viceroys are themselves distasteful because of compounds from their willow host plants, so the two species are co-mimics that share the cost of educating predators, a relationship called Müllerian rather than Batesian mimicry. Genuinely palatable mimics do exist: the red-spotted purple, the female black swallowtail and the dark female tiger swallowtail all copy the toxic pipevine swallowtail.

Behaviour. Erratic, dipping flight makes a butterfly hard to intercept, adults roost hidden under leaves at night, swallowtail caterpillars evert a foul-smelling orange osmeterium, and a chrysalis, which is covered in the guide to the butterfly pupa, will wriggle and click when touched.

Did you know?

• Two Mexican birds, an oriole and a grosbeak, eat over a million overwintering monarchs each winter despite the butterflies' toxins.
• Ants cannot catch a flying butterfly, yet they are probably the single biggest predator of butterfly eggs and newly hatched larvae.
• A caterpillar reared from the wild is as likely to produce a tachinid fly as a butterfly in many species, because parasitism rates commonly exceed fifty per cent.
• Viceroys were shown in 1991 to taste as bad to birds as monarchs, overturning a textbook example that had stood for a hundred years.
• Bird beak marks, a neat notch or a matching pair of triangular tears, are found on a large share of older butterflies, proof that eyespots and false heads work.
• Humans are predators too: caterpillars and pupae of several moth and butterfly species are traditional food in parts of Africa, Asia and Mexico.

In summary

Butterflies are eaten at every stage of life. Ants, ladybirds and tiny wasps take the eggs; birds, social wasps, spiders, bugs and parasitoid flies and wasps take the caterpillars; birds, mice and ichneumonids open the chrysalises; and birds, spiders, mantises, dragonflies, lizards and frogs catch the adults. Fewer than one egg in ten becomes a butterfly, and the survivors owe their lives to camouflage, eyespots, stored plant toxins with warning colours, mimicry and fast, erratic flight.

Frequently asked questions about butterfly predators

What animals eat butterflies?

Birds are the main predators of adult butterflies, followed by spiders, praying mantises, dragonflies, robber flies, assassin bugs, wasps, lizards, frogs, toads and mice. Eggs and caterpillars are eaten by ants, ladybirds, lacewing larvae, stink bugs, ground beetles and birds, and are also killed from the inside by parasitoid wasps and tachinid flies.

Do birds eat butterflies?

Yes. Flycatchers, swallows, warblers, jays, orioles and grosbeaks all take adult butterflies, and caterpillars are the main food of most nestling songbirds. At the monarch's winter roosts in Mexico, black-backed orioles and black-headed grosbeaks eat over a million butterflies each winter. Birds hunt by sight, which is why butterflies rely on camouflage, eyespots and warning colours.

Which stage of a butterfly's life is most vulnerable?

The egg, caterpillar and chrysalis stages, because none of them can fly away. Ants and tiny parasitic wasps destroy eggs, almost everything eats caterpillars, and a chrysalis that is found is opened by birds, mice or wasps. Adults are harder to catch and less rewarding, so once a butterfly has hardened its wings its chances improve greatly.

What percentage of butterflies survive to adulthood?

Usually fewer than ten per cent of the eggs a female lays, and in many field studies fewer than five per cent. A monarch may lay three to five hundred eggs to produce a handful of adults. Predators, parasitoids, disease and weather take the rest, with most deaths occurring in the first two weeks as an egg or small caterpillar.

What eats caterpillars?

Birds, paper wasps and yellowjackets, stink bugs, assassin bugs, ground beetles, spiders, lizards, frogs and small mammals all eat caterpillars, and parasitoid tachinid flies and braconid, ichneumonid and chalcid wasps kill even more by developing inside them. In many species parasitism alone removes more than half of the caterpillars in a season.

Do spiders eat butterflies?

Yes, at every stage. Crab spiders hide in flowers and seize adult butterflies by the head as they feed, orb-weavers catch them in webs, jumping spiders stalk small blues and skippers, and wolf and ground spiders hunt caterpillars and resting adults at night. Loose wing scales help some butterflies tear free from webs.

How do monarch butterflies protect themselves from predators?

By being poisonous. Monarch caterpillars store cardenolide toxins from the milkweed they eat, and those toxins remain in the adult. A bird that eats one vomits within minutes and afterwards avoids the orange-and-black pattern. A few predators, including two Mexican birds and a mouse at the winter roosts, have learned to tolerate or avoid the poison.

Is the viceroy a mimic of the monarch?

Yes, but not a harmless one. The viceroy was long described as a palatable butterfly that copies the toxic monarch, but feeding trials published in 1991 showed birds find viceroys just as distasteful, because of compounds from their willow host plants. The two species are therefore Müllerian co-mimics that share the same warning pattern and the cost of teaching predators.

Why do some butterflies have eyespots?

To deflect or startle predators. Large eyespots like those of the common buckeye make a bird hesitate or flinch, buying the butterfly time to escape, while small spots and tails at the hindwing edges of hairstreaks and blues form a false head that draws the strike to an expendable wing margin instead of the body. Bird-beak notches on wings show how often this works.

Do humans eat butterflies?

Adults are rarely eaten, but the caterpillars and pupae of various moths and butterflies are traditional foods in parts of southern Africa, Asia, Australia and Mexico, where they are fried, dried or added to stews. Most are moth larvae rather than butterflies, and toxic species such as the monarch are never eaten.

Published February 19, 2020 · Last updated September 21, 2026