Over half of Britain’s 57 resident butterfly species live on the Isle of Portland, because restored limestone quarries and wild flowers create a warm, protected home for them.
Chalkhill Blue
The largest of Portland’s six species of blue butterfly, the Chalkhill Blue is found on the chalk and limestone downs of southern England, but is not a common species. It prefers warm south-facing areas where there is an abundance of its larval food-plant, Horseshoe Vetch.
Sadly decreasing in other parts of Dorset, Portland is now a stronghold, and it can be seen on the wing from late July through August in many of the old quarries, and on the eastern undercliffs. The males are often observed seeking nectar on plants such as Knapweed and Carline Thistle.
Silver-studded Blue
An uncommon butterfly, mainly found on the heathlands of central and southern England, with Dorset and the New Forest particular strongholds.
There are scattered populations on the coasts of Cornwall, North Wales, and here on Portland, that are found in grassland, with the larvae feeding on Bird’s-foot Trefoil.
There are only a handful of populations remaining on Portland, mostly found in sheltered sites in and around old quarry workings. It is on the wing from early June to mid July.