IT may sound like something from the 1970s American disaster-horror film The Swarm but the spread of the Asian giant hornet, known as the "murder hornet", has sparked concern in Canada and the US.

What are they?

Big bad bees, basically. The insect is the world’s largest hornet, with a body length of about two inches. It is native to woodland and mountains in Asia. It as large as a man's thumb and has a bulky orange and black body.

Are they spreading?

Fears are growing that the hornet is spreading throughout the Pacific north-west of Canada and the US, following sightings. Last year bee keepers spotted and eradicated a nest on Vancouver Island, sustaining numerous painful stings in the process, the Guardian reported. Officials in Washington state in the US have now asked the public to report any signs of the creatures.

So, are they deadly?

Yes, but mostly to other bees. In rare cases, the hornet’s venom can lead to anaphylactic shock or cardiac arrest in humans. In Japan, the species is responsible for an estimated 30 to 50 deaths per year, according to the United States Department of Agriculture.

So what's the problem?

Experts fear the species could decimate North American bee populations, leading to ecological breakdown as bees are the world's most important pollinator of food crops. It is estimated that one third of the food that we consume each day relies on pollination mainly by bees. Across England, Scotland and Wales, a third of wild bees and hoverflies are in decline, a study found last year. Dr Gary Powney of the Centre for Ecology and Hydrology, said the long-term food security for Britain could be harmed.

These hornets spell trouble?

Perhaps but Doug Yanega, an entomologist at the University of California at Riverside, told the Los Angeles Times the bigger problem was people buying sprays and hornet traps. He said: “Millions and millions of innocent native insects are going to die as a result of this.”

How do hornets wipe out bees?

Asian giant hornets have been found to destroy entire beehives in a matter of hours, by decapitating the much smaller bees. “They have massive heads with these giant mandibles and they just chop them in half,” Gard Otis, a bee specialist at the University of Guelph told the Canadian Press. “They just cut their heads off, cut their bodies in half, and you end up with a slaughter on the ground in front of the hive.”

So what can be done?

Experts say the spread of the hornets can be contained if individuals are quickly tracked back to a nest and destroyed.

Could they come here?

They are not believed to have reached yet Europe. The Indepedent reported that the smaller Asian hornet has been spotted on numerous occasions in the UK since 2016, with a recent sighting in April in Guernsey. The Department of Environment, Food & Rural Affairs (Defra) has confirmed a total of 17 sightings of the smaller hornet in England, with the most recent sighting recorded in Dorset last year.

Garry Scott