Death's Head Hawk-moth - Les Evans-Hill

Hundreds of rare moths have flocked to the UK in what is being described as the best migration for years as a result of the recent record-breaking spell of warm weather.

The last few days have seen the largest influx of the rare Flame Brocade moth for 130 years, with experts also believing it has now set up a colony at a secret site in Sussex.

The arrival of a wide variety of species, many typically found in the Mediterranean, has led moth scientists at wildlife charity Butterfly Conservation to declare the autumn of 2011 as the best immigration season for more than five years.

Others immigrants drawn in by the Indian summer include a spectacular species made famous by horror film The Silence of the Lambs - the Death's-head Hawk-moth, the beautiful Crimson Speckled and the delicate Vestal moth.

But it is the occurrence of large numbers of Flame Brocade, a moth normally found in Spain and France, that could prove most significant.

This was first discovered by Butterfly Conservation Officer for Sussex, Michael Blencowe and his friend Graeme Lyons, when one of the moths turned up unexpectedly in a back garden at the weekend.

Mr Blencowe, 40, explained: "I'd never seen one of these moths before so I grabbed my net and went off to find out if there were any others about at a suitable site nearby.

"I saw 10 that night and there have been recordings of 20 or more there every night since."

Usually only single figures of Flame Brocades turn up in the UK each autumn, but this discovery of the beautiful, purplish-brown moth which boasts a distinctive white wing flash, has led to experts to suspect there may be a colony at the site.

Butterfly Conservation's Head of Moth Conservation Mark Parsons said: "The Flame Brocade was resident in Sussex for at least half a century from about the mid 19th century and a scarce immigrant since then.

"This is the first time the moth has been seen in these numbers in this country for about 130 years.

"This moth appears to have been making an attempt to re-colonise these shores, possibly as a result of more favourable overall weather conditions through climate change."

The Death's-head Hawk-moth, which boasts a striking skull like pattern on the thorax, has been seen along the South Coast at the RSPB's Arne nature reserve in Dorset and in Plymouth, Devon.

Large numbers of Vestal moths and several Crimson Speckled, both normally found in the Mediterranean, have also been seen on the South West and South East Coast, both also being seen in Gwynedd

And the extremely rare tropical species Spoladea recurvalis has been recorded from Ireland to the Isle of Man.

Mark Parsons explained: "This is beginning to look to be the best autumn for immigrant moths since 2006, both in numbers of scarce species and diversity."

"Amongst the highlights is Spoladea recurvalis. Prior to 2006 there had only been 19 records of this species in this country, with 19 recorded that year.

"More than 20 have been recorded so far this autumn, being found in Sussex, Dorset, Cornwall, Cumbria and the Isle of Man, additionally there have been the first records for Ireland.

"This is a widespread tropical species, its occurrence here this autumn being aided by the southerly winds."

But despite the influx of foreign species, it has been a relatively poor year for some of our rare native moth species which have struggled as a result of the record-breaking dry spring.