www.ukbutterflies.co.uk

I was wondering about this after seeing a fully-grown larva scrambling up a grassy bank, seemingly looking for a pupation site, in early September in south-west France. There were plenty more Peacock larvae of various sizes still feeding up on their nettles both in the immediate area and elsewhere in the region. Presumably any adults emerging would have already begun to do so and feeding-up for the winter might be possible.

Maybe it's a straggler from the earlier generation that has been affected by adverse weather conditions?

I believe they can.

In 2009 I found Peacock larvae in late August which duly hatched out into butterflies in September - and some reference books say that Peacocks may have two broods. The alternative is that a hibernated female was mated very late (after late emergence from hibernation because of the weather?) and only laid eggs at the tail end of the season.

Dave

Yes, Peacock can occasionally be double brooded in the UK - though not this year!
Neil