Big Butterfly Count is the largest insect citizen science project in the world.
Anyone can take part - simply count butterflies for 15 minutes during bright (preferably sunny) weather during the event, which runs from Friday 14 July to Sunday 6 August. The results help us see how butterflies are faring across the UK.
This nationwide survey is aimed at helping us assess the health of our environment. It was launched in 2010 and has rapidly become the world's biggest survey of butterflies.
Over 36,000 people took part in 2016, counting almost 400,000 individual butterflies and day-flying moths across the UK.
For more information, visit Big Butterfly Count.