This male was feeding on Viburnum tinus this morning
The adults feed on a range of nectar producing plants, I have compiled this list from several sources:
Aubrieta, Choisya, Buddleia, Hebe, Hyssop, Red Valerian, Ragwort, Garlic Mustard, Viburnum tinus, Bramble (Rubus fruticosus agg.), Bugle (Ajuga reptans), Buttercups (Ranunculus spp.), Forget-me-nots (Myosotis spp.), Holly (Ilex spp.), Honeydew / Sap, Ivy (Hedera helix), Privet (Ligustrum vulgare), Thistles (Cirsium spp. and Carduus spp.) and Water Mint (Mentha aquatica), Hemp-agrimony (Eupatorium cannabinum), Rosebay Willowherb (Chamerion angustifolium).
This is the weekly distribution of my records, clearly showing the presence of two flying generations: