A call has gone out to nature-lovers to help solve the mystery of Britain's declining moth population.
You can help by taking out a torch this weekend and counting the number and type of moths that come out at dusk.
It's feared that the number of the moths in the country has plummeted by 50% in the last 35 years.
Changes to how farmers work and the building of more towns and roads are among the things that have led to the decline.
Moths are important to the natural world.
Their caterpillars provide food for many birds, bats and other small creatures, so the decline could have a serious knock-on effect.
You can find out more about taking part in the moth count by clicking on the link on this page.