British bug population in free-fall

The number of flying insects in the United Kingdom may have halved since 2004, according to data from a citizen survey that counts dead insects found on license plates following car journeys.

The survey, which was run by insect conservation organization Buglife and the Kent Wildlife Trust, found the number of insect "splats "on license plates decreased in England by 65 percent between 2004 and 2021. Wales and Scotland saw a 55 percent and 28 percent decline, respectively, and there was not enough data to draw conclusions in Northern Ireland.

Only two major nationwide studies have been conducted using this method in the UK, so there is a chance insect populations experienced an unusual boom or bust during survey years. But the trend noticed was backed up by several other studies that show an alarming drop in insect numbers globally.

A 2019 systematic review of studies published in the journal Biological Conservation found that 45 percent of insect species were in population decline, at a rate of at least 2.5 percent per year. A long-running population survey in Germany, that uses special insect traps, found insect numbers had dropped by 76 percent during the last 27 years.

Insects play a vital role in functioning ecosystems, providing food for other animals, pollinating many of the world's crops and plants, and encouraging soil health. Scientists warn that plummeting insect populations could lead to environmental collapse in many regions around the world.

Paul Hadaway, director of conservation at Kent Wildlife Trust, said the UK survey "should shock and concern us all".

"These declines are happening at an alarming rate and without concerted action to address them, we face a stark future," Hadaway said.

In order to gather data, special "splatometer" grids were placed across the license plates of volunteers' cars. The grids were cleaned before car journeys, and volunteers then took photos after each time they had driven their vehicles and uploaded them on the Buglife app along with an estimated "splat" count.

Data from a similar survey in Denmark, which used car windshields, revealed an 80 percent decline between 1997 and 2017.

Matt Shardlow, chief executive of Buglife, said the survey suggests the number of flying insects in the UK is declining by an average of 34 percent each decade, a rate he described as "terrifying".

"We cannot put off action any longer, for the health and wellbeing of future generations, this demands a political and a societal response," he said.

An April study by University College London scientists suggested climate change was behind the population decline, along with the conversion of wilderness areas to agricultural land. The survey of more than 750,000 samples found insect numbers were 49 percent down in areas that had considerable climate warming and high-intensity agricultural land use compared to natural areas with no record of warming.