West Coast Scientists Encourage Public to Set Traps for Murder Hornets

Experts are calling for the public’s help in eradicating the invasive Asian giant hornet species—aka ‘murder hornets’—found in British Columbia and Washington state over the past two years,

Scientists at the U.S. Department of Agriculture and B.C. Ministry of Agriculture, Food and Fisheries said citizens are encouraged to lay out a mix of one cup of brown sugar and one cup of water to lure and trap these hornets, as the end of the species’ hibernation period approaches in April. 

This is a less expensive trap to set than the originally recommended bait of orange juice and rice wine, and only needs to be checked once every two weeks.

Asian giant hornets or Vespa mandarinia are native to East Asia. In North America, they pose a major threat to honeybee colonies and other local insect species which play a vital role in our ecosystems. 

They were first spotted on Vancouver Island, in the city of Nanaimo, in August 2019, where a nest was found and destroyed. Since then, Asian giant hornets and their nests have been discovered in Washington state and across the Fraser Valley in B.C. 

“We would like to use the public’s eyes to report sightings because we just don’t have enough resources to be everywhere all the time,” said Paul van Westendorp, an apiculturist with the B.C. Ministry of Agriculture, Wednesday. 

“If you have a trap near your house and you find some unusually large wasp or hornet-like creature in there, all that I would suggest is call [authorities] and we will deal with it.”

Murder hornets can grow up to five centimetres long, have a wingspan of up to seven centimetres, a six-millimetre-long stinger, and a large orange head. While they are not usually aggressive towards humans, a paper published by the University of Washington describes the sting of a murder hornet as “excruciating” and notes that unlike honeybees, hornets can sting repeatedly. 

Last year, public reporting in Washington state led to 31 sightings of murder hornets, and one of those insects was tracked back to a nest which was then eradicated.

In B.C., there were six sightings of the hornets in the Fraser Valley area in 2020, all reported by members of the public, but no actual specimens were collected last year despite the province setting 60 traps.

This year, provincial authorities will once again be setting traps to catch Asian giant hornet specimens, using either a pheromone or an orange juice-rice wine mix. 

The goal is to catch a live hornet, tag it, and then track it back to its nest which can then be destroyed. Last year, a nest containing 200 queen murder hornets, each capable of starting its own colony, was discovered in a tree above a child’s play set in Blaine, Washington. 

“Having something that could really cause you a serious world of hurt, unbeknownst to you, living on your property—that is really what puts you in danger,” said Sven-Erik Spichiger, managing entomologist at the Washington State Department of Agriculture. 

“So hanging a trap actually protects you. It lets you know that there's something in the area and contains it in such a way that you can then call [authorities in B.C. or Washington] and we can do something about it.”

In addition to tracking and eradicating these apex predators, scientists in the U.S. are conducting whole genome sequencing to figure out how Asian giant hornets arrived in North America and whether there are any genetically unique subpopulations. 

“Knowing the origin is important to control efforts because it may offer a better understanding of nesting biology and potential range, which varies in native populations,” said Anna Childers, a researcher at the U.S. Department of Agriculture.

Childers says they are also collaborating with other agencies in the U.S. and scientists in Japan to identify chemicals to which the hornets are particularly sensitive in order to develop better synthetic traps.

In B.C., the Ministry of Agriculture has involved various agencies—including municipalities, parks and recreation staff, and First Nations—in the search for Asian giant hornets in 2021, after a disappointing season last year.

“This is a formidable task. We have been genuinely frustrated by not getting enough of these darn hornets in our hands,” said van Westendorp.

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