They are a quintessential sign of summer - the scent of blossom on the wind and the buzzing of bees. But scientists claim that both are now under threat - as flowers lose their natural scent due to pollution.
Gases from car emission are dulling floral aromas and disrupting insect life, says study
This is preventing flowers from attracting bees and other insects needed to pollinate them.
As a consequence, the numbers of insects are dramatically dwindling as they struggle to located the nectar off which they feed.
Professor Jose Fuentes, of the University of Virginia, which carried out the research, said: "Scent molecules produced by flowers in a less polluted environment could travel for roughly 1,000 to 1,2000 metres.
"But today they may only travel 200 to 300 metres. "This makes it increasingly difficult for bees and other insects to locate the flowers."
The study, funded by the US National Science Foundation, examined the smell given off by snapdragons.
They found that the scent molecules are volatile and quickly bond with pollutants, such as ozone and nitrate radicals - formed mainly from vehicle emissions. This chemically alters the molecules so that they no longer smell like flowers.
As a result, bees and other insects - which rely on the scent of flowers to locate them - fail to do so and do not get enough food.
The ability of the insects to attract mates and repel enemies is also impeded, scientists fear.
While the flowers, which rely on insects to pollinate them, also suffer. Scientists have found that bees, which pollinate most of the world's crops, are in unprecedented decline in Britain and across much of the globe.
At least a quarter of America's 2.5million honey bee colonies have been wiped out by colony collapse disorder (CCD) where hives are found to be suddenly deserted.
Although the mysterious phenomenon has yet to appear in the UK, insect numbers have been declining here too.
Agricultural minister Lord Rooker has warned that "the honey bee population could be wiped out in 10 years".
The scientists do not believe pollution is necessarily the cause of CCD but they claim it is making it harder for many insects to survive.
Research shows it is not just insects that are affected by the actions of humans. The number of birds visiting our gardens and parks has plunged by a fifth in four years, a survey has revealed.
The decline follows a succession of mild winters and the growing popularity of paving and decking, which robs gardens of valuable plants and insects.