I’m a big favourite with Cornwall’s sand dune visitors in the summer months.
Silver-studded blues look very different depending on their sex; the male wings are a bright silvery blue with a dark border, and the females are brown with orange spots at the edges of the wings, sometimes with a blue tinge too. Adult butterflies will flutter over the dunes during the summer, finding sheltered patches of bare ground or very short vegetation on which to lay their eggs. This species actually like to lay eggs where ants live nearby, or at the mouth of an ant colony, as ants often look after the eggs during the winter and as they turn to caterpillars in the spring. They’ll become a pupa around June and a fully-winged adult in June, July and August.
The caterpillars produce a sweet juice which attracts the ants and encourages them to take care of it, protecting it while it grow.
Look out for silver-studded blues flying and feeding not far from the ground during the daytime in June and July. As a caterpillar, they eat birdsfoot trefoil on the dunes so look out for this plant with small yellow flowers. In the early evening the adult butterflies will roost in groups on bushes or long grasses. This species can be found at Gwithian and Mexico Towans in Cornwall.
By encouraging rabbits, ponies or cattle to graze the landscape, we can help keep vegetation and grasses short and encourage wildlfowers to grow which suit silver-studded blues, but some areas of bushes will be left as these are used for shelter and roosting.
Projects protecting Silver-Studded Blue Butterfly
At Penhale, you can’t miss these eye-catching dunes, standing around 90 metres above sea level, they’re pretty tall for a dune system. On the north coast of Cornwall near the town of Perranporth, Penhale Dunes are part of the Cornish Killas National Character Area and a designated Site of Special Scientific Interest (SSSI). The wide and sandy, three kilometre-long Perran beach in front provides sand for the dune system, which is blown up into the dunes by the wind.
Further reading: A Review of the Silver-studded Blue in Cornwall 2020
Published in 2020, this report includes:
- 2020 Silver-studded Blue SpeciesNet Report, by Sally Foster - Biological Surveyor
- Silver-studded Blue Phenology Analysis, by J Dennis M.Sc