North America's bee crisis escalates as murder hornets crop up where they've already been eradicated

There are growing concerns over the rise of murder hornets in North America, after their presence was discovered in regions of Canada and the US that had both previously eradicated them.

The Asian giant hornet - which entomologists have dubbed the 'murder hornet' - can grow to more than 5cm long and are native to Japan, where their highly venomous stings are responsible for an average of 50 deaths a year.

They made landfall in North America last year, and are causing major headaches for biosecurity officers concerned that they'll annihilate bee colonies and kill people.

Bees are a major food source for murder hornets, which are significantly larger than other hornet, bee or wasp species. They decapitate bees, then take the severed thoraxes back to their offspring, who feed on them.

Their discovery last year has seen biosecurity teams deploy a range of containment measures - but despite their best efforts, murder hornets have recently re-emerged in two areas where they were believed to be wiped out: Canadian province British Columbia and US state Washington.

British Columbia thought it'd eradicated them last August, after local beekeeper Conrad Bérubé destroyed a nest using carbon dioxide - although not before a series of powerful stings, which he suffered despite wearing multiple pairs of pants, chainsaw braces and a Kevlar vest.

However this week a woman living 13km away from Nanaimo, where the nest was located, reported a strange-looking insect in her home. Experts have since confirmed it was a murder hornet.

"This particular insect has acquired a larger distribution area at this time than we had thought," apiculturist Paul van Westendorp told the New York Times.

In Washington, a few murder hornets were recently discovered a few kilometres south of a beehive that was decimated by the invasive species last year.

The new discoveries mean field workers will likely have to expand their trapping areas, at a greater cost to taxpayers.

It's not known how the murder hornet made it to the US and Canada, 10,000km away from Japan, but there are major concerns its presence there could further annihilate bee colonies, which have already been decimated in recent decades.

recent study estimates one in every three bites of food is made possible by bees. A reduction in bee numbers could hit the US, one of the world's largest food producers, particularly hard.

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