On sunny October days many butterflies are still on the wing. Small coppers (Lycaena phlaeas) and speckled woods (Pararge aegeria) fly late in the year, but two species in particular are especially obvious now.
Red admirals (Vanessa atalanta), which have a bold slash of scarlet across their forewings, and bright orange commas (Polygonia c-album), whose outline resembles a dead leaf, are very fond of over-ripe fruit.
Both species sleep overwinter but before they settle down they stock up on sugars, which they get from the nectar of late flowers, such as Michaelmas daisies, and from rotting fruit.
Look under apple or plum trees in sunny spots and colourful flashes will alert you to red admirals and commas feeding on fermenting fruit. You may even be able to observe a butterfly at close quarters.
That’s because the sugar in the fruit converts partly into ethanol, which makes the insects woozy and dulls their senses. Really sozzled butterflies can even be picked up.
Commas are well-established as overwinterers in the UK and are spreading northwards, but for red admirals this is a riskier strategy.
Large numbers of red admirals migrate here each year and until recently they used to fly south or perish in winter. But in recent years many of them are surviving the milder winters and emerging successfully in spring. They will even fly on mild sunny days in December and January.
Identify any butterflies you see feeding using the Butterfly Conservation Trust ID guide.
Illustration: Rose Sanderson