More than 3,000 painted lady butterflies on their annual 1,000 mile migration from Africa have been spotted at a nature reserve in Gloucestershire.
Sightings of the insects have been reported across the UK. Wardens said the creatures like the rough grasslands at the reserve in Slimbridge.
Butterfly Conservation believe this is the largest migration of the species in over a decade with more expected.
The butterflies originate from the Atlas Mountains of Morocco.
James Lees, a warden at the Slimbridge Wildfowl and Wetlands Trust, said: "It's truly amazing to stand on the River Severn and see thousands of these small dainty butterflies flying past all heading in the same direction.
"It is remarkable that despite being lighter than paper they are able to navigate and travel thousands of miles over land and sea."
He added that painted ladies preferred rough grasslands with knapweed and thistle and that the reserve was currently covered in wild flowers and wild clover which provided "these butterflies with excellent refuelling snacks during their epic migration."
Dr Martin Warren, of the conservation charity, Butterfly Conservation, said: "There are literally millions of painted lady butterflies arriving right across Britain with more expected this weekend.
"We need the public's help to get better information on the nature and scale of this spectacular and unprecedented migration."
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