Experts found and then captured two 'murder hornet' queens after returning to finish clearing out a nest in Washington.
In an operation on 24 October, entomologists eradicated the first-ever discovered US nest of the giant Asian insect after they were discovered in Blaine, north of Seattle.
Members of the Washington State Department of Agriculture's (WSDA) Pest Program returned on Wednesday to remove a portion of the tree where the wasps had been nesting.
'As we were cutting it down yesterday, two queens emerged from the tree. They could be two virgin queens or one virgin queen and the queen that actually started the nest,' said Karla Salp, a spokesperson for the agency.
'We do not know if they were both virgin queens or not. That's something we're looking into over the next several days,' she added.
In footage captured during the operation, a worker can be heard saying: 'Any more than one queen is not good news.'
Pictured: One of the queens discovered during the operation last Wednesday in Blaine, Whatcom County, Washington
Pictured: Both queens discovered during the operation last Wednesday in Blaine, Whatcom County, Washington
Pictured: A worker from the WSDA's Pest Program prepares to remove a section of the tree the murder hornets were nesting in
Once the section of the tree was removed, the agency transported it to the Washington State University Puyallup Research and Extension Center to be kept in a walk-in cooler to make the hornets docile.
The scientists pumped carbon dioxide into the tree on Thursday in order to split the log and analyze its contents.
'Once it opened, then we started removing Asian giant hornets that were still in the nest. They appeared, at least some of them, alive,' Salp said.
Scientists also found larvae on the nest's comb.
They said they won't have a final tally of the hornets until they're able to count all of them.
Entomologists first discovered the Asian giant hornet nest in a tree cavity on private property in Blaine, Whatcom County, close to the US-Canada border on 22 October.
The insects had set up camp inside the cavity on the land that had been cleared to build residential property on.
The WSDA closed in on the insects last month when experts captured and attached tracking devices to some of the hornets.
Pictured: One of the queens captured from the tree in Washington. In a Facebook post, the WSDA said they managed to vacuum 85 live hornets from the nest. All of them will be studied for research
Entomologists attached radio trackers to three insects using dental floss and waited for one of them to lead them to the nest.
The second hornet was traced to the nest where experts then watched dozens of hornets entering and exiting the tree.
'While Asian giant hornets normally nest in the ground, they are occasionally found nesting in dead trees,' the WSDA said in a statement.
'Dozens of the hornets were seen entering and exiting the tree while the WSDA team was present.'
It was about 300 yards (274 meters) from the traps in the cavity of a tree on private property, officials said.
A worker from the Washington State