The Wildfowl and Wetlands Trust has urged wildlife lovers to get involved in the Big Butterfly Count.
Any reported sightings will go into a national record which will be used to determine whether populations are growing or declining.
The count comes as Butterfly Conservation president Sir David Attenborough warned that UK butterfly numbers are at an historic low, with 2012 being the worst year on record for UK butterflies.
Anyone interested in taking part in the count, which runs until August 1, can contact WWT Castle Espie Wetland Centre, which has specific habitats that support butterflies.
For more information go to www.bigbutterflycount.org.