Scientists scaling up efforts to prevent murder hornets from settling into U.S., Canada

Scientists are upping their efforts to stop so-called murder hornets and their bee-killing ways from settling into North America.

The Asian giant hornets have been found in Whatcom County, Washington, and Fraser Valley in British Columbia, where agriculture officials are working on setting traps and studying the invasive species as spring kicks off.

“This is not a species — Asian giant hornet — that we want to tolerate here in the U.S. and certainly not in Washington state,” said Sven-Erik Spichiger, an entomologist with the Washington State Department of Agriculture.

He added that a homeowner whose report about the hornets led the department to a nest last year took photos of them preying on wasp nests at his residence.

“We don’t know what kind of consequences that would have if Asian giant hornets were to become established and take out, say, all wasps in the area,” Mr. Spichiger said last week. “Certainly, when you remove one of the species from the ecosystem, it’s going to have impacts. We just don’t know what those are at this time. My policy is, let’s not find out because the Asian giant hornet isn’t supposed to be here anyway.”

Paul van Westendorp of the British Columbia Ministry of Agriculture, Food and Fisheries said the hornets could pose a risk to more people, wildlife and livestock, and threaten honey bees and other insects if they manage to make themselves at home in North America.

Hornet queens usually emerge in early spring and form nests filled with workers that grow in size around July into December, Mr. Spichiger said. During the summertime, hornets will start looking for a source of protein, such as honey bees, as they expand their colonies.

This hornet season, the Washington State Department of Agriculture will set up 1,500 traps, or about one trap per kilometer, using mostly orange juice and rice cooking wine as bait. The department also will offer residents a brown sugar and water mix as bait.

British Columbia will set up more than 60 traps due to increased activity in Washington state, Mr. van Westendorp said. The province will conduct comprehensive surveys in areas where hornets were spotted before, including Nanaimo and the Cowichan Valley on Vancouver Island.

Last year, there were 31 confirmed sightings of the hornets in Washington state, not including the 500 found in the nest detected and eradicated in Blaine in October, Mr. Spichiger said. British Columbia confirmed six sightings.

The Asian giant hornet was first detected around Vancouver Island in August 2019.

Researchers have been studying hornets captured in North America and comparing them to those found in South Korea, Japan and China. Genetic evidence suggests the hornets in the U.S. closely match those in South Korea, while those in British Columbia are similar to hornets in Japan, Mr. Spichiger said. Scientists are trying to determine if the hornets were introduced to North America on separate occasions.

Experts say the hornets likely traveled through maritime shipments.

However, it is unknown if the hornets migrated directly from those countries, said Anne LeBrun, a scientist for the U.S. Department of Agriculture. The agency is studying the hornets and working on creating new lures for traps.

The first confirmed detection of an Asian giant hornet in Washington occurred in December 2019. The first hornet was trapped last July followed by the capture of several more, all in Whatcom County, which is in the northwest corner of the state and about 60 miles from Fraser Valley.

Asian giant hornets are the world’s largest hornets, reaching just over 2 inches in length, and feed on honey bees and other insects. The invasive pests also spit venom and deliver painful stings that can damage tissue. While these insects are usually nonaggressive, they will sting people who disturb them.

The hornets at most kill a few dozen people a year in Asian countries. In the U.S., an average of 62 people die each year from hornet, wasp and bee stings, according to the Centers for Disease Control and Prevention.