Any blue butterfly seen fluttering several feet up around shrubs, trees, along hedgerows or in gardens in southern Britain is likely to be a Holly Blue. This is not a sure means of identification however. The most distinguishing feature in both sexes is the underwing, which is clear silver blue with tiny black dots and no orange marks. It gives the Holly Blue a distinctly silver look in flight and makes it unmistakable at rest. Only the Small Blue is similar, but this is very much smaller and has sooty upperwings. The upperwings of the Holly Blue are violet blue - indeed the male resembles a male Common Blue from above. The female upperwings are more distinctive because they have wide dark borders and tips.

Dimensions:
Adult wingspan: 26-34mm.

National:
The Holly Blue is found throughout England and Wales. While widespread it is never numerous.

At Durlston:
It is not uncommon on the Park with most occurring around the woodland areas of the east sector. Numbers in the west sector are presumably centred in the Gully.

It normally has two generations in the south of its range. The first generation larvae feed on Holly Ilex aquifolium while the second generation feeds on Ivy Hedera helix. The eggs are laid on flower buds and the larvae burrow into these and feed. They pupate out of sight and the second generation overwinters in this stage. The first generation is active from late March to late June while the second generation is on the wing from mid July to mid September.