More than 500 Asian giant hornets have been collected from the first known nest of the invasive species in the United States, officials announced Tuesday.
Washington State Department of Agriculture entomologists discovered the nest of "murder hornets" last month in a tree in Blaine, north of Seattle, near the Canadian border.
After eradicating the nest, during which the crew vacuumed out nearly 100 hornets, the entomologists removed the portion of the tree with the nest and opened it the following week to collect any hornets that had remained. The crew had pumped carbon dioxide into the tree during the nest removal to kill or anesthetize any remaining hornets, and many were still alive, officials said.
Upon opening the tree, the team determined that the nest was about 14 inches long and up to 9 inches wide. Hornets in various life stages were collected, including approximately 200 queens, Sven Spichiger, the agency's managing entomologist, told reporters during a virtual press briefing Tuesday.
"As far as we can tell, we got there just in time," Spichiger said. "We know from the literature that a small percentage of these will go on to form colonies next year, should they have been given the chance to escape."
In total, the nest contained 190 larvae, 112 worker (female) bees, nine drone (male) bees and six unhatched eggs, Spichiger said. There were 76 queen bees, and 108 capped cells with pupae, most of which were believed to be of new virgin queens.
Spichiger said there is "no way of knowing" how many queens there were in total, and if any had escaped.
"From accounts we have, we're very close to having the majority of them," Spichiger said of the queen bees, who typically produce most of the bees in a hive. "But I can't give you an absolute, certainly, that we got every single one from the nest."
The findings from the Blaine nest come about a month after the first giant hornet was detected in the region. The agency placed live traps in the area in early October after a homeowner reported a specimen, Spichiger said.
Four live hornets were caught in the traps, after which entomologists were able to attach radio trackers to three of them, and one led them to the nest -- located in the cavity of a tree on private property -- on Oct. 22.
After the team observed dozens of hornets entering and leaving the tree, the property owner gave the agency permission to eradicate the nest and, if necessary, remove the tree, officials said.
On Oct. 24, the agency announced that that the removal of the nest "appears to have been successful," and that 85 specimens were vacuumed out of the nest.
Despite this success, state entomologists believe there are additional nests in the state, based on additional specimens captured in different regions.
Hundreds of traps have been set throughout Washington by agriculture department staff, scientists and others, in an attempt to eliminate the pest from the state. At 2 inches, the world's largest hornet can kill an entire honey bee hive in just hours. With bee populations already in decline in the U.S. due to what's known as "colony collapse disorder," the killer hornets pose another threat to the ecosystem if they become established over several years.
Agency officials say they'll continue to keep their traps up through Thanksgiving, at which point it typically becomes too cold for the hornets to fly. But Spichiger said it's possible they could find another nest before the end of the year, as the first hornets in the state were detected last Dec. 8.
"The more people are outside and looking at this time of year, the more chances we have," he said.
Officials said the agency will continue to trap for at least three more years to ensure the region is hornet-free -- and to prevent the insects from becoming a costly problem.
"Just look at gypsy moths," Spichiger said. "In the East, when gypsy moths get out of control, it costs millions of dollars. At least for long term, the smart path here is to eradicate it if we can."
The invasive species has been found as far away as British Columbia, though the "epicenter" appears to be in Washington, experts said.
For humans, the giant hornet's sting is more painful than that of a typical bee or wasp, and people are advised to use caution near the insects and not attempt to remove or eradicate nests themselves.
It's not known how the killer hornets, which are native to Asian countries including China and Japan, arrived in the Pacific Northwest -- but a likely theory is that they came in via international cargo. Another less likely theory is that someone smuggled the hornets in to raise them as food, Spichiger said.
"These are sought-after food items in their native range," he said. But, he added, "I think most people don't want to travel with such a thing."