Atala (Eumaeus atala)

In this guide

1. Description and identification
2. Life cycle: egg, caterpillar, chrysalis and adult
3. Where the atala butterfly lives
4. Host plants and diet
5. Behavior and flight
6. Similar butterflies and how to tell them apart
7. Quick facts
8. Did you know?
9. Pictures
10. Frequently asked questions

Description and identification

The atala is a hairstreak, a member of the gossamer-winged butterfly family, but it breaks most of the rules of the group. Hairstreaks are usually small, grey or brown, tailed, and hard to notice. The atala is jet black, scattered with metallic blue-green, carries a patch of scarlet on the body, has no tails at all, and makes no attempt to hide. It can afford to advertise, because its body is loaded with a poison it took from its food plant as a caterpillar.

Adult butterfly

• Wingspan: 1.5–2 in (38–51 mm), large for a hairstreak but still a small butterfly.
• Underside: this is the view you normally get, because the atala sits with its wings closed. The ground is deep velvety black. Three curving rows of iridescent blue to blue-green spots cross the hindwing, and a single bright red-orange blotch sits near the base of the hindwing, close to the body.
• Upperside: black with a wash of metallic scaling. In males the iridescence is usually a blue-green or teal sheen spread over much of the wing; in females it tends to be a deeper, more royal blue concentrated on the forewing, with broader dark margins. The exact tone shifts with the angle of the light, because the color is structural rather than a pigment.
• Abdomen: the tip is bright red-orange, a flag that stays visible even when the butterfly is feeding with its wings shut.
• Sexes: very similar in pattern. Females average a little larger, and males a little smaller and more heavily marked with green.
• No tails: unlike most hairstreaks, the atala has no hindwing tails and no false-head markings, because it does not depend on deflecting attacks.

How to identify an atala in the field

In southeastern Florida there is nothing else quite like it. Look for a small, dark butterfly fluttering slowly and low around a coontie bed, in gardens, parks, dune edges and hammock margins. The combination of a black underside, arcs of metallic blue-green spots and a scarlet spot at the hindwing base plus a scarlet abdomen tip is diagnostic. If the flight looks lazy and moth-like and the butterfly seems entirely unbothered by your presence, that is the atala too.

Life cycle: egg, caterpillar, chrysalis and adult

In the subtropical climate of south Florida the atala breeds continuously, with overlapping generations all year and a peak after the summer rains push out new growth on the host plants. A single cycle from egg to adult takes roughly six to eight weeks.

Eggs

Unlike most hairstreaks, the female does not lay one egg at a time. She places her eggs in clusters, commonly of five to twenty or more, on the soft new leaves of a coontie, usually on the underside or along the frond stalk. Each egg is pale cream to white, about 1–1.5 mm across, and its surface is finely sculptured rather than smooth. They hatch in about four to six days, and the young larvae stay together.

Caterpillar

Newly hatched larvae are pale and almost colorless, and they darken quickly once they start feeding. The mature caterpillar is unmistakable: a stout, velvety crimson to scarlet body carrying two neat rows of bright yellow spots along the back, reaching about 1.5 in (38 mm). There is no camouflage in this design at all, and none is needed. The larvae take up cycasin, an azoxyglycoside produced by the cycad, and store it in their tissues, so the color is a genuine warning rather than a bluff.

Atala caterpillars feed in loose groups, several to a frond, and prefer new growth, which is softer and more nutritious. A heavy brood can strip a coontie, although an established plant regrows from its underground stem. Most lycaenid caterpillars are tended by ants in exchange for sugary secretions; the atala has no such arrangement, which fits a larva that is already chemically protected and has little to gain from bodyguards.

Chrysalis

When it is ready to pupate the larva usually leaves the plant and settles on a nearby stem, wall or leaf litter, often alongside others, so a dozen pupae may be found within a hand's width of each other. The chrysalis is short and rounded, girdled upright with silk, and coloured from a golden or reddish brown to a much darker chocolate brown, patterned with fine black speckling. The adult emerges after roughly two weeks. The pupa is toxic as well, and wasps and lizards that learn this once tend to leave them alone.

Adult butterfly

Adults live about two to four weeks, which is a long life for a butterfly of this size and reflects how little they need to hide. They emerge, harden, and are usually mating within a day or two. Females spend much of that time searching for coontie with fresh growth, and because they lay in batches, a single female can seed a whole colony on one garden bed.

Where the atala butterfly lives

The atala is a butterfly of southeastern Florida, the Bahamas and Cuba, with historical records from the Cayman Islands. Within the United States it lives only in that narrow strip of southeastern Florida, from roughly Martin and Palm Beach counties south through Broward and Miami-Dade into the Keys. It is not found anywhere else in the country, and reports from further north almost always turn out to be another dark hairstreak.

Its natural habitat is pine rockland, coastal strand, sand scrub and the edges of tropical hardwood hammocks, all places where wild coontie grows in sandy, well-drained soil. Today most colonies are somewhere else entirely: landscaped gardens, school grounds, office parks, roadside plantings and butterfly gardens where coontie has been used as an ornamental. The butterfly is effectively an urban specialist now, and the map of its distribution follows the map of coontie planting more closely than it follows any natural habitat.

Host plants and diet

Caterpillar host plants. The atala is a cycad specialist. Its main host in Florida is coontie, Zamia integrifolia, a low, fern-like native cycad with a thick underground stem; the plant is often listed under its older name Zamia pumila, which properly belongs to a related Caribbean species. Ornamental cycads in the same genus are used readily, and cardboard palm (Zamia furfuracea) is regularly colonised in gardens. These plants belong to the family Zamiaceae rather than the true cycads of the family Cycadaceae, and the butterfly will not normally accept sago palm.

Why cycads matter. Coontie tissue contains cycasin, a compound toxic to vertebrates, and the underground stem is so loaded with it that Indigenous peoples of Florida and early settlers had to grate, soak and repeatedly wash the starch before it was safe to eat. The caterpillar eats the leaves and keeps the toxin, carrying it through the pupa and into the adult. The scarlet larva, the red abdomen tip and the reluctance of birds to touch any stage of this butterfly all follow from that one chemical.

Adult diet. Adults drink nectar, and they are not selective. Spanish needles, lantana, wild coffee, buttonsage, porterweed, periwinkle and palmetto blossom are all worked regularly, and they forage low and slowly, often returning to the same flower patch day after day. Adults do not feed on the host plant itself, so a garden needs both coontie for the larvae and open nectar flowers for the butterflies.

Behavior and flight

Flight. The atala flies slowly, weakly and close to the ground, with a fluttering wingbeat that looks more like a day-flying moth than a hairstreak. It rarely travels far, and colonies stay tied to a host patch for years. That unhurried flight is not a weakness but a consequence of its chemistry: a butterfly that predators avoid has no reason to spend energy on evasion. Our page on butterfly colors covers how warning signals like this one work.

Warning coloration. Every stage advertises. The egg cluster is exposed, the caterpillar is scarlet, the pupa is not hidden, and the adult sits in the open with a red flag on its abdomen. This is aposematism in its clearest form, the same strategy the monarch uses with milkweed toxins, worked out independently on a completely different plant group.

Roosting and daily rhythm. Adults are most active in the warm middle of the day and settle in the late afternoon, often several together on the same shrub or frond, where they spend the night with wings closed. They bask with wings partly open on cool mornings, which is the easiest time to see the metallic upper surface.

Broods. There is no diapause and no migration. Breeding runs all year in south Florida, with several overlapping generations, and colonies can boom quickly. A patch of coontie that looks untouched in spring can carry hundreds of caterpillars by late summer, and the population then crashes back as the plants run out of new growth.

Similar butterflies and how to tell them apart

Quick facts

Did you know?

• The butterfly was named after Atala, the heroine of Chateaubriand's 1801 novella of the same name, at a time when naturalists routinely borrowed from literature for species names.
• Its recovery is one of the few butterfly conservation stories driven almost entirely by ornamental horticulture. Nobody set out to save it; landscapers simply liked coontie.
• The poison in its body is the same reason coontie starch had to be washed for days before people could eat it. The caterpillar solved that problem by keeping the toxin instead of removing it.
• It is a hairstreak with no hair streak. The thin tails and false-head markings that give the group its name are absent here, because a protected butterfly does not need to trick a predator into striking the wrong end.
• Cycads are among the oldest seed plants on Earth, so the atala feeds on a lineage far older than the flowering plants nearly every other butterfly depends on.
• Egg clusters are the reason a colony appears so suddenly. One female laying batches on a single coontie bed can produce a mass of caterpillars where there was nothing a week earlier.

In summary

The atala is a small, slow-flying black hairstreak of southeastern Florida, the Bahamas and Cuba, marked with rows of iridescent blue-green spots and a scarlet flash on the abdomen. Its crimson, yellow-spotted caterpillars feed in groups on coontie and other Zamia cycads, storing the plant's cycasin so that every stage of the life cycle is poisonous and every stage advertises the fact. Nearly lost from Florida when coontie was stripped from the landscape, it survives today largely in planted gardens, which makes it one of the few butterflies whose future is decided in a plant nursery.

Atala butterfly pictures

Frequently asked questions about the atala butterfly

What does an atala butterfly caterpillar look like?

It is a stout, velvety caterpillar of bright crimson to scarlet, carrying two neat rows of yellow spots along its back, and it reaches about an inch and a half. There is no camouflage in the design. The colors are a warning that the larva is loaded with cycasin taken from the cycad it eats.

Why are atala caterpillars so brightly colored?

Because they are genuinely poisonous. Feeding on coontie, the larvae absorb and store cycasin, a toxin the cycad makes to defend itself, and they keep it through the pupa and into the adult. Scarlet and yellow advertise that fact to birds and lizards, a strategy called aposematism, so the caterpillar can feed in the open.

How do you identify an adult atala butterfly?

Look for a small black butterfly, one and a half to two inches across, sitting with its wings closed. The underside shows three arcs of metallic blue to blue-green spots on the hindwing and a single bright red spot near the wing base, and the tip of the abdomen is scarlet. There are no hindwing tails.

Is the atala butterfly endangered in Florida?

It is not federally listed today, but it came very close to disappearing. After coontie was harvested out of the landscape for its starch, the butterfly was thought lost from Florida until a colony was rediscovered on Key Biscayne in 1959. Widespread planting of coontie as an ornamental has since brought it back across southeastern Florida.

What do atala caterpillars eat?

Only cycads in the genus Zamia. In Florida the main host is coontie, Zamia integrifolia, a low native cycad with a thick underground stem, and garden cycads such as cardboard palm are used as well. The larvae prefer soft new growth and feed in loose groups, several to a single frond.

What does the atala chrysalis look like?

It is short and rounded, held upright against a stem or wall by a silk girdle rather than hanging. The color ranges from golden or reddish brown to a much darker chocolate brown, finely speckled with black. Pupae are often found in small clusters, because the caterpillars leave the plant together to pupate.

Where does the atala butterfly live?

Its range covers southeastern Florida, the Bahamas and Cuba, with old records from the Cayman Islands. In the United States it is confined to the strip from about Martin and Palm Beach counties south through Broward and Miami-Dade into the Keys, wherever coontie grows wild or has been planted.

Is the atala butterfly poisonous to humans?

It is toxic to predators, not to people in any practical sense. The cycasin it carries would be harmful if eaten in quantity, but the butterfly cannot bite or sting and the caterpillar has no irritating hairs or spines. Handling one is safe, although washing your hands afterwards is sensible with any insect.

How can I attract atala butterflies to my garden?

Plant coontie in a sunny, well-drained spot for the caterpillars, and add nectar flowers such as Spanish needles, lantana, wild coffee or porterweed for the adults. Skip insecticides entirely, and accept that fronds will be eaten. An established coontie regrows from its underground stem after a brood has stripped it.

How long does an atala butterfly live?

Adults live roughly two to four weeks, long for a butterfly this small, because predators mostly leave them alone. The full cycle runs about six to eight weeks: four to six days in the egg, three to four weeks as a caterpillar and around two weeks as a chrysalis, repeating all year.