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This topic is being opened again in order to provide a location to collate overwintering sightings of the immature stages of the Red Admiral. The last few winters have produced a lot of valuable data from across the country, much of it in time to be included in the book Life-cycles of British and Irish Butterflies

Starting with 19th and 20th October, I observed a lot of egg-laying on nettles growing in sheltered south-facing locations at Lancing on the Sussex coast, with further sightings inland at Knepp by Neil Hulme.
There were also several larval tents in the same locations in Lancing.

Interesting adult movements have also been observed. On 19th October, Red Admirals were seen flying south through Midhurst, Sussex (against the wind) by Dave Harris. The following day the wind direction changed to a northerly and numerous butterflies were seen coming in off the sea (again against the wind) at Lancing (by me), Newhaven (by Bugboy) and at Seven Sisters (Twitter), all on the Sussex coast. Apparently, according to research published in the 1958 book, Insect Migration by CB Williams, the preferred direction for insect migrational flight (not just of butterflies) is into the wind, with the second most preferred direction being with a tail wind (via Dave Harris).

On 27th October, butterflies were again seen coming in off the sea at Newhaven cliffs by Dave Harris (again against the wind).

Vince

A walk along the seafront today at Lancing on the Sussex coast produced 3 Red Admirals. One was laying many eggs in a sheltered spot; one was on the beach and another was flying determinedly north (against the wind).

The temperature during these observations was 9C in sunny conditions and with a cool northerly wind.

Vince

This has been a poor winter for finding overwintering eggs and larvae. It has been mild and very wet and the strong winds have smashed down plants, making observations even harder. A personal disinclination to trudge around in the terrible conditions has not helped either. Only one report of a pupa found by Dave Harris in his Newhaven garden on 23rd February.

Edit: A butterfly emerged from this pupa on 28th March and the remainder had hatched by 21st April. The pupal stage was estimated to last between 4 and 7 weeks in this batch. These April butterflies emerged at the same time as influxes started to arrive from the continent.

The only other observation came from Paul Harfield who reported on the overwintering habits of some adults in his garden last November viewtopic.php?f=29&t=6085&start=780#p149428

Vince