A blue butterfly is more than a quick flash of color. It is a small reminder of how delicate and resilient nature can be. Their wings can shimmer from soft sky blue to deep sapphire, creating some of the most striking colors found among butterflies.
One fascinating example is the Karner blue butterfly, a tiny federally endangered butterfly found in parts of the northern United States. Its survival is closely tied to wild lupine, the only plant its caterpillars eat. This close relationship makes the Karner blue an interesting example of how butterflies depend on healthy habitats to survive.
Blue butterflies come in many species, sizes, and shades, each with its own characteristics and life history. In this article, we’ll explore beautiful blue butterflies, where they live, what makes their coloring so remarkable, and some fascinating facts about these eye-catching insects.
- Also see Blue and Black Butterfly.
Types of Blue Butterfly
1. Karner Blue (Plebejus melissa samuelis)
- Location: Great Lakes region and northeastern United States
- About: The Karner blue butterfly is a small, federally endangered butterfly. Males have silvery to dark blue upper wings, while females are generally brownish with areas of blue and orange markings. Its caterpillars feed exclusively on wild lupine (Lupinus perennis). Karner blues depend on open habitats such as oak savannas and pine barrens where wild lupine grows.
2. Common Blue (Polyommatus icarus)
- Location: Europe, parts of North Africa and Asia
- About: The Common Blue is one of Europe’s most familiar blue butterflies. Males generally have bright blue upper wings, while females can range from mostly brown to partly blue. They are commonly seen in grasslands, meadows and other open areas.
3. Blue Morpho (Morpho spp.)
- Location: Central and South America
- About: The blue morpho butterfly is famous for its large wings and brilliant shimmering blue appearance. Its color is largely structural—the microscopic architecture of its wing scales interacts with light to produce the intense blue. When the wings close, the brownish undersides help the butterfly blend into its surroundings.
4. Adonis Blue (Lysandra bellargus)
- Location: Europe
- About: Male Adonis Blues are known for their brilliant blue wings bordered by dark markings, while females are generally brown with orange markings and varying amounts of blue. This species is particularly associated with warm, flower-rich calcareous grasslands.
5. Small Blue (Cupido minimus)
- Location: Europe and parts of Asia
- About: Despite its name, the Small Blue isn’t always strikingly blue. Males usually have dark brown upper wings dusted with bluish scales, while females are predominantly brown. In Britain, it is the country’s smallest resident butterfly species, and its caterpillars depend strongly on kidney vetch.
6. Azure Butterflies (Celastrina spp.)
- Location: North America and other regions, depending on species
- About: Azures are delicate butterflies with pale blue or violet-blue coloration. Several species occur in North America, often around woodland edges, gardens and flowering shrubs. Because similar-looking azure species can overlap geographically, identification sometimes requires more than wing color alone.
Why Are Some Butterflies Blue?
The brilliant blue seen on many butterfly wings does not always come from blue pigment. In species such as Blue Morphos, microscopic structures in the wing scales interact with light, reflecting certain wavelengths and creating vivid blue colors. This is known as structural coloration.
The appearance can change depending on the angle of the light and the viewer, which helps explain why some blue butterfly wings seem to shimmer or shift in intensity as the butterfly moves. Different species produce their blue coloring in different ways, making these wings as fascinating scientifically as they are beautiful.
7. Ulysses Butterfly (Papilio ulysses)
- Location: Australia, Papua New Guinea and nearby islands
- About: Also called the Ulysses swallowtail, this spectacular blue swallowtail butterfly has brilliant electric-blue areas surrounded by black on its upper wings. Its large size and vivid coloring make it one of the most recognizable tropical butterflies in its range.
8. Eastern Tailed-Blue (Cupido comyntas)
- Location: North America
- About: The Eastern Tailed-Blue is a small butterfly distinguished by tiny tails on its hind wings and orange spots near those tails. Males generally show more blue on their upper wings, while females are often brownish or grayish. It occurs in many open habitats, including fields, roadsides and meadows.
9. Silvery Blue (Glaucopsyche lygdamus)
- Location: North America
- About: The Silvery Blue is a small butterfly whose males display pale, shimmering blue upper wings. Females are usually darker. It can be found in a variety of open habitats, including meadows, prairies and woodland openings, with caterpillars using plants in the pea family.
10. Palos Verdes Blue (Glaucopsyche lygdamus palosverdesensis)
- Location: Palos Verdes Peninsula area of Southern California
- About: The Palos Verdes Blue is an extremely rare subspecies of the Silvery Blue. Once feared extinct, it was rediscovered in the 1990s. Conservation efforts have included captive breeding, habitat restoration and reintroduction work designed to help protect the remaining population.
11. Long-tailed Blue (Lampides boeticus)
- Location: Africa, Europe, Asia and Australia
- About: The Long-tailed Blue has slender tails on its hind wings and small eyespot-like markings near the tails. Males generally show more blue-violet coloration than females. Its caterpillars feed on numerous plants in the pea family, which has helped the species occupy a very broad geographic range.
- Also see Blue Morpho Butterfly.
Why Blue Butterflies Matter
Blue butterflies are more than beautiful insects. Like other butterflies, they are part of the ecosystems they inhabit, interacting with plants and other wildlife throughout their life cycle. Some species have very specific habitat requirements, which can make them especially vulnerable when those habitats disappear or change.
The Karner blue butterfly, for example, depends on wild lupine during its caterpillar stage, while other blue butterfly species rely on different host plants and habitats. Protecting native plants, meadows, grasslands, forests, and other natural areas can therefore benefit butterflies along with many other insects and animals.
Whether you’re watching a tiny Eastern Tailed-Blue in a meadow or admiring the brilliant wings of a Blue Morpho, these butterflies show just how diverse the natural world can be. Learning to recognize different species is a great first step toward appreciating—and protecting—the habitats they need to survive.