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The small blue is our smallest British butterfly and is an indicator of chalk grassland in good condition. It’s wings are brown, fringed with white, with a fine layer of blue scales spreading out from the body. The undersides of the wings are grey with dark spots and a slight blue colour again spreading out from the body. The adults fly between mid-May and early July and there may be a second generation in high summer. The caterpillar foodplant is kidney vetch.
The small blue is protected under the Wildlife and Countryside Act (1981) and is a UK Priority Species for conservation. It is a rare butterfly found mainly in south-central England though it can also be found along some eastern Scottish coasts and both the east and west coast of Ireland. It is very localised in distribution and its range has declined by 44% since the 1970s.
Chalk Grassland
Chalk grassland (or lowland calcareous grassland) is a habitat of international importance for both its rarity and its species richness. It is found over limestone and chalk rocks and grows below an altitude of 250 metres on shallow, lime-rich soils, mainly in the warmer, drier south and east of the UK. As many as 40 different plant species can be found within a square metre. Many of them are so specialised that they can be found only in chalk grassland where they are specially adapted to the thin, infertile but base-rich soils. Characteristic features of the habitat often include ant-hills and, on steep slopes, terracettes or sheep walks. Small patches of scrub add to the habitat diversity by providing bird-nesting habitat and song-posts.
The UK holds around 50% of the world’s surviving chalk grassland with major concentrations on the North and South Downs of south-east England. Formerly widespread in these areas, an estimated 80% had disappeared by WWII and only 1% of the Surrey Hills has remnant chalk grassland cover.
This will benefit a wide range of other specialist chalk grassland plants including other vetches such as horseshoe vetch, orchids such as bee orchid and pyramidal orchid, wild marjoram, dropwort, small scabious and many others. It will also benefit their associated insects such as other blue butterflies.
Surrey Hills Society has been facilitating several volunteer groups (including Surrey Choices Growth Team, Halow, Defra and Butterfly Conservation) to help with the restoration of chalk downland at the Hampton Estate, Puttenham. This involves removing inappropriate tree species (such as Hawthorn) from the chalk downland using tree poppers. Once this work has been completed, Butterfly Conservation are planning to plant kidney vetch, the foodplant of the Small Blue butterfly caterpillar. It is hoped that this will help to bolster the population of Small Blue butterflies and contributes to a wider restoration project taking place along the North Downs, which is being coordinated by Butterfly Conservation. Enhancement of chalk downland habitat will also help to benefit a whole range of other butterfly and pollinator species.
These illustrations are by an artist taking part in a programme delivered by Watts Gallery Trust and funded by the Michael Varah Memorial Fund. This series of 30 Surrey Hills Indicator Species were commissioned by Surrey Hills Society and funded by Surrey Hills Trust Fund as part of the Making Space for Nature Exhibition.