Know Before You Go

The rarest blue butterfly in the UK, this endangered species has recently recolonized areas of the Cotswold where it had been considered extinct for over 40 years. From May to September, this species can be found on sunny, south-facing grassland rich in herbs, where they search for their solitary food source, horseshoe vetch.

The males are a vivid sky-clue with fine black lines around the perimeter of their wings, which gives way to a delicate white fringe. Females of the species are much less vibrant, predominantly appearing brown, although some variation has been seen.

The lifecycle of the Adonis blue features a fascinating symbiotic relationship with ants. There are two broods a year, in the spring and fall, which find eggs laid on small plants in short turf. This creates a warm microclimate and easy access for the ants, which tend to the larvae, protecting them from predators and parasites in exchange for the secretions from special ‘honey’ glands. This remarkable relationship often continues through the pupal stage, when adults will finally emerge from the ant colonies in which they have been incubated.

The decline of the Adonis blue was attributed to a loss of suitable habitat, particularly during the production of the second generation in late fall. There has been a marked effort to improve awareness around maintaining suitable habitat, and many conservation groups are working directly with farmers to manage pasture in a way that creates suitable habitat for this rare species.