By Alex Kirby
BBC News Online environment correspondent
A novel way of gauging how widespread insects are across the UK suggests they are less common than many people think.
Lucky bug: This hoverfly avoided being hit by a vehicle (Image: Grahame Madge, RSPB)
The Royal Society for the Protection of Birds asked volunteers for its Big Bug Count to see how many insects crashed to their doom on vehicle number plates.
Nearly 40,000 participated and the RSPB says the data shows one insect died every 8km (five miles), far fewer than expected.
It says the findings could be bad news for some bird species, though they do not prove that insects are declining.
Not many victims
The Big Bug Count, which the RSPB says was the first survey of its kind in the world, asked people to count the number of insects splattered over their number plates after a journey during June (a routine journey, not a special one).
They were asked to use a splatometer, a cardboard grid developed by the RSPB and registered by it as a trademark.
The organisers say many people were astonished by how few insects they splatted. A total of 324,814 insects were counted at an average rate of only one splat every 8km (five miles).
Richard Bashford, the count co-ordinator, said: "The main aim of the survey was to form the baseline against which we would compare data from future years.
"Although variation in insect numbers across the UK was small, there appears to be a gradual increase in numbers from the south-east of England to Scotland.
"The reasons for this, and the potential consequences for birds, will be the focus of future research.
Searching for evidence
"Because this is a new survey we can't show for sure that insects have declined. However, in order to see if there are any changes in insect populations in the future, the RSPB will repeat this survey.
"In time we will be able to compare these results with those from our bird monitoring to see if there are any links."
Many birds depend on insects, either in their own diet or as food for their chicks. Swallows and house martins are specialist insect feeders, but seed-eating birds like skylarks and house sparrows also need insects for their young.
THE BIG BUG COUNT
There are more than 23,000 insect species in the UK
Worldwide there are maybe 4-6 million more
Insects are needed for pollinating crops and plants
A swallow needs to eat thousands of insects a day
Many of the species which rely on insects have declined in recent years, with house sparrow numbers falling by 65% since 1973.
Besides the Big Bug Count, there are three major long-term insect studies in the UK. Rothamsted Research runs a series of large suction traps that suck insects from the air.
The Rothamsted Insect Survey also runs a network of light traps to look at moth populations across the country, and butterflies are monitored nationally by the Centre for Ecology and Hydrology.
Theories to explain possible insect declines include habitat loss and pesticide use.