The silver-studded blue is a heathland specialty and the New Forest is one of its strongholds.
It is found throughout the New Forest but you will only see it in a few other places in the UK, such as Dorset, the Surrey heaths, Cornwall and west Wales. It is restricted to these areas because it is very choosy about its habitat.
In the New Forest, silver-studded blues are quite common on large areas of heathland. They require a habitat where there is plenty of young heather due to higher levels of grazing, clearance or a fire. The other thing they require is the black ant Lasius niger. The caterpillars secrete a sweet substance that the ants feed on; in return the ants look after the caterpillars, tending them, carrying them about and protecting them from insect predators. They even pupate in the ants’ nest: rows of silver-studded blue pupae have been found along the passages and brood chambers of ants’ nests in the New Forest.
The best places to look for silver-studded blues are on large areas of open heath with some damper spots during July and August. If you see a blue butterfly follow it and wait for it to land, then creep up slowly for a closer look. Sudden movements will scare them off.