What Do Butterflies Eat?

Butterflies are among the most recognizable pollinators on earth — but what they eat is more surprising than most people realize. Yes, nectar from flowers is the main food source for most adult butterflies. But they also drink tree sap, slurp salts from mud puddles, feed on rotting fruit, and in some species, pull nutrients from animal tears, sweat, and dung.

This guide covers everything about butterfly diets — how they eat, what they drink, what their caterpillars need, and how to feed butterflies in your own yard. For more on butterfly-moth relatives, see our what do moths eat guide.

The Short Answer: What Do Butterflies Eat?

Adult butterflies eat a liquid-only diet. They have no jaws or teeth — just a long, coiled, straw-like tongue called a proboscis that uncurls to sip liquids. Their diet consists of:

• Flower nectar — the primary food source for most species
• Rotting or overripe fruit — high in sugars as it ferments
• Tree sap — oozing from wounds or fresh cuts on trees
• Mud puddle minerals — salts, nitrogen, amino acids
• Honeydew — sugary secretions from aphids
• Pollen — only a few species like Heliconius longwings
• Animal fluids — tears, sweat, urine, and dung in some tropical species

Caterpillars — the butterfly larval stage — have completely different mouthparts and diets. They have chewing jaws and eat leaves and other plant matter voraciously, each species restricted to specific host plants.

How Butterflies Eat: The Proboscis

Butterflies don't eat — they drink. Instead of a mouth, an adult butterfly has a proboscis, a long, flexible tube made of two interlocking halves that act like a drinking straw. When not in use, the proboscis coils tightly into a spiral under the butterfly's head. When the butterfly finds food, the proboscis uncurls and extends into the flower.

The proboscis can be remarkably long — in some tropical species longer than the butterfly's entire body — which lets butterflies access nectar tucked deep inside flowers that bees and other pollinators can't reach. This is why butterfly-adapted flowers often have long, tubular shapes.

"Butterflies taste with their feet. Sensors on their feet can detect sugars at concentrations 200 times lower than human taste buds, letting them identify a suitable flower the instant they land."

Adults vs. Caterpillars: Two Completely Different Diets

One of the most important things to understand about butterfly nutrition is that adults and caterpillars are essentially different animals, with entirely different mouthparts, foods, and nutritional needs.

This is why a truly butterfly-friendly garden needs two kinds of plants: nectar plants for adults, and caterpillar host plants for the larvae. Without host plants, the butterflies visiting your yard will never produce a next generation there.

What Do Caterpillars Eat?

Caterpillars eat leaves — and they eat a lot of them. A single monarch caterpillar will eat about 200 times its own body weight during its roughly two weeks as a larva. They multiply in mass up to 2,700 times between hatching and pupating.

The catch: most butterfly caterpillars are highly specialized. They can only eat specific host plants — often just one or two plant genera. If those plants aren't available, the caterpillars starve, no matter how much other vegetation surrounds them. This is why butterfly populations collapse when native host plants disappear.

Common North American butterflies and their caterpillar host plants:

• Monarch — milkweed (Asclepias species) only
• Black Swallowtail — parsley, dill, fennel, Queen Anne's lace
• Eastern Tiger Swallowtail — wild cherry, tulip tree, birch, ash
• Painted Lady — thistles, mallows, legumes (over 100 species)
• Red Admiral — nettles
• Question Mark — elm, hops, hackberry, nettles
• Spicebush Swallowtail — spicebush, sassafras
• Pipevine Swallowtail — pipevine plants only

What Do Monarch Butterflies Eat?

The monarch deserves its own section because it's the most famous and most endangered butterfly in North America — and its diet is uniquely restrictive.

Monarch caterpillars eat only milkweed. Period. The plant contains toxic compounds called cardenolides that would poison most animals, but monarch caterpillars have evolved not only to tolerate the toxin but to store it in their tissues, making themselves poisonous to predators. Without milkweed, there are no monarchs.

Adult monarchs drink nectar from a wide variety of flowers — milkweed blooms, goldenrod, aster, ironweed, Joe-Pye weed, zinnia, and many others. Adults are flexible generalists; caterpillars are absolutely not.

This is why monarch conservation groups push so hard for native milkweed in every yard: the U.S. Fish & Wildlife Service has documented that monarch population declines track directly with milkweed loss from roadsides, farmland edges, and urban landscapes.

Beyond Nectar: Tree Sap, Fruit & Honeydew

While nectar is the primary food for most butterflies, several common North American species actually prefer other food sources — and some rarely visit flowers at all.

Rotting and Overripe Fruit

Fallen apples, pears, bananas, peaches, and other soft fruit become prime butterfly food as they decompose. Question marks, commas, mourning cloaks, red admirals, hackberry emperors, and viceroys are more likely to be found on rotting fruit than on flowers. The fermenting sugars are easy to access with a proboscis, and the pulp provides moisture.

Tree Sap

Fresh sap oozing from tree wounds is a butterfly magnet. Sap flows are especially important in early spring before flowers bloom and in late fall after nectar sources dwindle. Mourning cloaks, one of the first butterflies seen each spring (they overwinter as adults), rely heavily on sap flows from maples and birches.

Honeydew

Honeydew is the sticky, sugar-rich liquid that aphids and other sap-feeding insects secrete. Where aphid populations are high, butterflies will feed directly on the honeydew-coated leaves. This is one reason to think twice before spraying for aphids — you may be eliminating a food source.

Mud Puddling Explained

If you've ever seen a cluster of butterflies — sometimes dozens — gathered at the edge of a mud puddle, a damp gravel path, or a creek bank, you've witnessed mud puddling. This is one of the most fascinating butterfly behaviors and has nothing to do with water.

Nectar is essentially sugar water. It fuels flight but provides almost no salts, minerals, nitrogen, or amino acids — all of which butterflies need for reproduction. To get those essential nutrients, butterflies visit damp soil, sand, or puddles and drink the water to extract dissolved minerals. They sip for long periods, excreting excess water out the back as they process the liquid.

The males pass these minerals to females in a "nuptial gift" during mating. The female then uses those nutrients to provision her eggs, which means puddling directly affects reproductive success. This is why you often see large puddle clubs of mostly male butterflies.

The Weird Stuff Butterflies Eat

Butterflies are more opportunistic than their dainty reputation suggests. Some of the strangest but documented food sources include:

• Sweat and tears — butterflies land on sweaty skin, faces, and even the eyes of large animals to drink salty fluids
• Dung and urine — fresh animal droppings are packed with nitrogen; butterflies feed on them readily
• Rotting carrion — some tropical butterflies feed on decomposing animals
• Aphid bodies — the Harvester butterfly (the only carnivorous butterfly in North America) pierces woolly aphid bodies and drinks their fluids
• Blood — certain tropical species have been documented drinking blood from open wounds on animals

This isn't gross — it's survival. Butterflies need compounds they can't get from flowers, and biology pushes them to every source available.

Do Butterflies Drink Water?

Yes, but not the way mammals do. Butterflies get most of their water directly from nectar and other liquid foods. When they do drink water specifically, it's almost always for the dissolved minerals rather than hydration — which is what mud puddling is.

On very hot days, you may see butterflies sipping dew, light rain on leaves, or water at the edges of bird baths. If you want to offer water to butterflies in your yard, the most effective method is a shallow dish of wet sand or a muddy depression — not a clean bird bath. Clean water is much less attractive than mineral-rich muddy water.

Best Plants for Feeding Butterflies

If you want butterflies in your yard, plant a combination of nectar sources for adults and host plants for caterpillars. Natives are almost always better than exotics because local butterflies evolved with them.

Emergency Butterfly Feeding: Sugar Water Recipe

Occasionally, you might find an exhausted or cold butterfly unable to fly. If the butterfly is uninjured but clearly weak, a simple sugar water solution can give it enough energy to recover. This is widely used by butterfly rescuers and nature centers.

Seasonal Butterfly Diet Changes

Butterflies are active in distinct phases through the year, and their diet shifts with what's available.

Early spring: Few flowers are blooming when overwintered adults like mourning cloaks and question marks emerge. They depend heavily on tree sap, fermenting fruit left from winter, and the earliest flowers like pussy willow and hepatica.

Late spring through summer: Peak butterfly activity. Adults feed on a wide variety of flowers. Caterpillar populations explode as host plants leaf out.

Fall: Goldenrod, aster, and ironweed are the critical late-season nectar sources. Migrating monarchs rely on these to fuel the multi-thousand-mile journey to Mexico.

Winter: Most North American butterflies overwinter as eggs, caterpillars, chrysalises, or adults in a state of suspended animation (diapause). A few migrate. Only in the Deep South, Florida, and coastal California do butterflies remain active year-round — where they continue feeding on whatever is in bloom.