The term “Meadow Blue” can be confusing as it is an informal name for several species of blue-hued butterflies. Depending on the continent, the name might apply to different insects, such as the Common Meadow Blue (Cupidopsis cissus) in Africa or the Eros Blue (Polyommatus eros) in Europe. To provide clarity, this article will focus on the Common Blue butterfly (Polyommatus icarus), one of Europe’s most widespread and frequently encountered blue butterflies in meadow habitats.
Recognizing the Meadow Blue Butterfly
The Common Blue butterfly (Polyommatus icarus) is a small butterfly with a wingspan between 29 and 36 millimeters. A distinguishing feature is that sex determines coloration. Males display a uniform violet-blue on their upperside, framed by a narrow black border and white fringes on the wing edges. This blue is a structural color, created by wing scales that reflect light in a specific way.
Females are more variable in appearance, often brown with a dusting of blue scales near the body. They feature a distinct row of orange, crescent-shaped spots along the margins of their wings. In some regions like Ireland and Scotland, females can be almost as blue as the males but always retain the orange marginal spots. The underside of both sexes is greyish-brown, covered in black spots circled in white and a series of orange marks that help in identification.
Where Meadow Blues Thrive
True to its name, the Common Blue is highly adaptable and thrives in a wide array of grassy, open habitats. It is found in flower-rich meadows, unimproved grasslands, coastal dunes, woodland clearings, and on disturbed ground like roadside verges and railway embankments. The butterfly shows a preference for chalk or limestone grassland, but its generalist nature allows it to colonize diverse environments from sea level up to high alpine meadows.
This species is one of the most widespread butterflies in Europe, with a range that extends from North Africa across the continent and temperate Asia to Northern China. It is prevalent throughout the British Isles. It forms distinct colonies in suitable locations where its larval food plants are abundant, and its ability to use a variety of habitats allows it to persist even in semi-urban areas.
The Life Journey of a Meadow Blue
The life cycle of the Common Blue has four distinct stages, with the number of generations per year varying by climate. In southern regions, it can have two or even three broods, while further north, a single generation is typical. The cycle begins when a female lays single, white eggs on the young foliage of various legumes (Fabaceae family), with Common Bird’s-foot-trefoil (Lotus corniculatus) being a primary choice.
After about a week, a small, green caterpillar emerges and begins to feed on the underside of the leaves. These larvae have a relationship with ants, which are attracted to a sweet secretion the caterpillars produce. In exchange for this “honeydew,” the ants provide protection from predators. The caterpillar overwinters as a half-grown larva in leaf litter before resuming feeding in the spring. Pupation occurs on the ground or at the base of the host plant, with the chrysalis lasting about two weeks before the adult butterfly emerges.
Meadow Blues in the Ecosystem
Within its grassland ecosystem, the Common Blue plays a multifaceted role. As adults, they are active pollinators, feeding on nectar from a wide range of wildflowers like clovers, buttercups, and knapweeds, which facilitates the reproduction of these native meadow species. The butterflies, in all stages of their life cycle, are a food source for various predators, including birds, spiders, and other insects.
Despite its widespread distribution, the Common Blue has faced declines in some areas due to habitat loss from agricultural intensification. The loss of wildflower-rich grasslands is a significant threat. The species is not currently of major conservation concern and is listed as Least Concern by the IUCN in Europe. The preservation of its meadow and grassland habitats is important for supporting its populations.