Sir David Attenborough urges public to count butterflies
18 July 2014 Last updated at 11:00 BST
Sir David Attenborough has called on the public to go out and spend 15 minutes counting butterflies in their local area.
Speaking ahead of the launch of the Big Butterfly Count, Sir David said it was an "invaluable" example of citizen contribution to science.
Sir David added that indications from caterpillar numbers were "exciting" ahead of this year's count.
Broadcast on BBC Radio 4's Today programme on Friday 18 July.