The number of bees in the UK is declining at an alarming rate, yet there are few explanations.
The invertebrate charity, Buglife, have suggested that the decline in native and wildflower rich grassland could be a cause.
Environment correspondent Sarah Mukherjee reports from the Hartslock Nature reserve in South Oxfordshire.
Sarah Mukherjee is leaving the BBC for pastures new.
Listen to a selection of Sarah's brilliant reports.