This week is Small Blue Butterfly Week across Scotland, with voluntary action by enthusiasts in Aberdeenshire, Moray, Irvine, Caithness and the borders. About a third of the world’s butterfly species belong to the blue family, that includes the hairstreaks, the Northern Brown Argus and coppers - other small butterflies with striking metallic colours. Many of these frail gems have an intimate relationship with ants. The large blue butterfly became extinct in Britain in 1979 but thanks to a major effort involving taking stock of its dependence on ants, was re-introduced and currently survives precariously in England. To date attempts to reintroduce the large copper, for which the last British record was in 1864, have failed.

A sign in Nairn mentions that the small blue is a size that would fit on a penny.

By contrast with the restricted range of some of the 20 or so blues in Britain, the Small Blue has a distribution that spans from the Caithness coast to the south west of Ireland. Despite this it has been described as "rare in almost every region it inhabits". This is so in the Cairngorms National Park. Here inStrathspey, unlike other parts of Scotland, we can boast having an inland, rather than coastal, population of Small Blue. Vital to the survival of the Small Blue is the foodplant Kidney Vetch, on which the caterpillars entirely depend. This plant with attractive yellow flowers seems to be a favourite for other insects, like bumblebees.

A bumblebee visits kidney vetch at a flower rich site supporting small blue in Strathspey.

During Small Blue Butterfly Week hopes are high that members of the public will spot and report sightings of Small Blue. Good places to look are where the vital food plant kidney vetch is growing in sheltered sunny spots. The 2002 Cairngorms Local Biodiversity Action Plan identifies calcareous, neutral and acid grassland as habitat for the small blue, but unfortunately delivering better conservation in the face of damaging land use change for these grasslands remains somewhat fraught with challenges.

The upper wings of a female small blue here on a flower of bird's foot trefoil in Strathspey are dark in colour.

Those wishing to see Small Blue this week but not having luck in Strathspey could consider a trip to some of the undeveloped dune slacks along the Morayshire coast, in places like Nairn that boasts around 20 butterfly species. If Morayshire is too far, the Landmark Centre at Carrbridge has a butterfly house with many colourful South American butterflies to admire. However, as the blue family is tricky to propagate in captivity it is not one of the butterfly families on show in this new butterfly house.

A male small blue in Strathspey has wings that show some blue scales.