Blue butterflies, with their striking colors, often capture human attention and spark a common question about their prevalence. Many believe they are exceptionally uncommon. However, the reality is complex: some species are widespread, while others face genuine threats. This article explores the difference between their actual ecological status and public perception.
The Widespread Presence of Blue Butterflies
Many blue butterfly species are common and can be observed across various geographical regions. The Common Blue butterfly (Polyommatus icarus) is widely distributed across Europe, parts of Asia, and North America, thriving in meadows, grasslands, and disturbed habitats. Males display bright blue wings, while females often show more brown coloration with orange spots. The Blue Morpho (Morpho menelaus) is a large, recognizable blue butterfly found in tropical forests of Latin America. Its iridescent blue wings, spanning up to eight inches, are a result of microscopic scales reflecting light, not blue pigment.
Other common blue species include the Eastern Tailed-Blue, found across North America, and the Silvery Blue. The Ceraunus Blue butterfly is also common in some regions, identified by its light blue upperwings and gray undersides with white bands. These butterflies adapt to a range of environments, and their widespread presence demonstrates that not all blue-winged species are rare.
The Truly Elusive: When Blue Butterflies Are Rare
While some blue butterflies are common, other species are genuinely rare or endangered due to specific ecological requirements or habitat loss. The Karner Blue butterfly (Plebejus samuelis), for example, is federally listed as endangered and has experienced population declines of over 90% in some areas since the 1970s. Its survival depends entirely on the wild blue lupine plant, as its caterpillars feed exclusively on its leaves, restricting the butterfly to specific dry, sandy habitats like oak savannas and pine barrens. Habitat destruction from urbanization, agriculture, and fire suppression are primary reasons for its decline. Climate change also poses a threat by disrupting their life cycle.
Another endangered species is the Fender’s Blue butterfly (Icaricia icarioides fenderi), rediscovered in 1989 after being thought extinct. Its rarity stems from its strict reliance on Kincaid’s lupine for feeding, with little of its original prairie habitat remaining due to conversion to farmland. The Large Blue butterfly (Phengaris arion) became extinct in the UK in 1979 due to agricultural changes impacting its complex life cycle, which involves specific wild thyme plants and a particular ant species. Small Blue butterflies (Cupido minimus) are also rare and localized, found only in specific grasslands where their sole food plant, Kidney Vetch, grows.
Perception vs. Reality
The perception that blue butterflies are rare often contrasts with their actual prevalence, influenced by factors beyond their true population numbers. Many blue butterflies, especially smaller species, have brief adult flight periods, making them visible for only a limited time each year. For instance, the Small Blue butterfly is active primarily from mid-May to late June, making its observation window narrow. This short activity period can make them seem less common.
The small size of many blue butterflies also contributes to their perceived rarity. Species like the Small Blue are easily overlooked. Their dusky or brown undersides, displayed when at rest or in flight, can make them blend into their surroundings, reducing visibility. Furthermore, some blue butterflies inhabit specific, less accessible environments, such as dense tropical forests or particular types of grasslands, which limits public encounters. The brilliant blue coloration of species like the Blue Morpho is structural, meaning it changes with light and angle, making them appear to flash or disappear as they fly, contributing to their elusive nature.