The gardener looked up at the tree in shock. 

Caught in a trap was a single brown insect. The gardener gulped in horror. Then he was hit by a terrible putridUnpleasant and repulsive. Emitting a smell of decay or rotting.  smell.

Across Britain, farmers are preparing for an invasion. The brown marmorated stink bug - scientific name halyomorpha halys - may only be the size of a fingernail, but it has already wreaked havoc across North America and Europe.

This summer, scientists spotted the stink bug in Britain for the third timeThe stink bug was found in a garden and tourist attraction in Surrey, England. Scientists do not know if the three insects were brought in on imported products or part of local populations. . Experts warn the hitchhikers, which are native to Asia, could be widespread across the UK within a decade.

It is bad news for Britain's crops. Stink bugs suck the juice out of fruit plants, destroying raspberries, peaches, pears and plums and deforming their seeds. In the US, the bugs cause millions of dollars in losses every year. 

They also invade homes, creeping in through tiny cracks in windows and doors. But worst of all is the smell they release from their knees, described as a "cross between rotting rubbish and rancid almonds". 

Yet some experts say we should not be so quick to demonise the stink bug. 

In 2013, a group of American researchers concluded that stink bugs may actually play a positive role in ecosystems. By wounding plants and allowing the sap to leak out, stink bugs provide food for vital wasps and ants. 

"When we try to pick out anything by itself, we find it hitched to everything else in existence," argued the 19th-Century nature writer John MuirMuir is known as "Father of the National Parks" for advocating for the preservation of wilderness in the USA. . It is a view shared by Merlin Sheldrake, an author and mycologist obsessed with fungi. 

Fungi are all around us. We see them in mushrooms, molds, infections and wood-root. Sometimes, they disgust us. The spores of the ophiocordyceps take over ants as parasites, forcing them to clamp their jaws to the underside of a leaf, from where the fungi grows. 

But in his book, Entangled Life, Sheldrake points out that humans need fungi. They eat rubbish and clean oil spills. They provide minerals for plants, are used in cooking and medicine and can even change the weatherSpores in the air attract moisture, which then form raindrops or hail. . 

Some nature lovers go further. Many humans have a utilitarianA school of ethics that focuses on maximising people's happiness and minimising their suffering. view of nature. Some philosophers argue the value of all living creatures exceeds the value humans place on them. 

"Rats are public enemy number one," declared Britain's chief rat catcherJohn Davison is the former CEO of Britain's National Pest Technicians Association.  at the height of a rat invasion in Yorkshire. They are blamed for human plagues and disease. Rats feature in nightmaresIn the dystopian novel 1984, Winston Smith's greatest fear is being taken to a chamber of rats. and horror films. 

But even the rat catcher admits he admires rats. "They are very intelligent, very astute - I respect them." In China, people born in the year of the rat are celebrated for creativity, honesty and ambition.

Sheldrake, too, loves fungi for more than just practical reasons. He is fascinated by their strange shapes and extraordinary abilities.

Some zoologistsScientists who study animals and their behaviour. think it is time to give insects - including stink bugs - the respect they deserve. People should ask not "what can they do for us" but "what can we do for them?" 

Definitely, say some. Malaria-carrying mosquitos are responsible for more than one million deaths every year. Plagues of locusts devastated crops across Africa in 2020. Now, the invasive stink bug is likely to cause similar chaos - and a terrible stench - in Britain. 

No, say others. Every creature has its own role to play. Spiders, feared by 45% of Britons, capture mosquitoes in their webs and create silk so strong it is used for bandages. Deadly foxgloves are used to treat heart conditions. And even when a creature is not useful for humans, it should still be valued as a part of nature.