What the WSDA found in the Asian giant hornet’s nest – PCT


More than 500 specimens of Asian giant hornets at various stages of development were collected when entomologists found the first Asian giant hornet nest in the United States.

But finding the nest was only the first step towards extermination. After discovering the nesting site, WSDA entomologists had to safely remove any hornets living in the nest, remove the tree, and finally split the tree to reveal the nest inside.

After the tree with the Asian giant hornet’s nest was opened on October 29th, the WSDA entomologists still had a lot of work to do to collect data on the contents of the nest. Similar to the election, the count has taken some time and is partially continued.

  • The nest was a little over eight feet tall in the tree and, once opened, was about fourteen inches long and eight to nine inches wide. Here are the preliminary results of what our entomologists found in the nest.
  • 6 honeycombs – There were six honeycomb layers in the nest. Combs are the structures that hold hornet larvae as they develop. Part of the inside of the tree had been chewed away to pick up the combs.
  • 776 * cells – The honeycombs are made up of cells and each individual cell can hold a developing Asian giant hornet. * This number is an approximate value as the combs have been damaged.
  • 6 Unhatched Eggs – These eggs were all in the last and smallest of the combs.
  • 190 larvae in total – The larvae are whitish “maggots” in cells without a cap. Many had fallen into the tree cavity when the nests were removed from the combs.
  • 108 cells capped with pupae – pupae are the next stage after the larvae. Based on the size of the cells, it is believed that most of the pupae found are pupae of new virgin queens.
  • 112 workers – This total includes 85 workers sucked from the nest on October 24th. All workers survived when they were sucked from the nest.
  • 9 Drones – Drones are male hornets and they generally hatch from the nest before the new queens appear.
  • 76 Queens – Most likely all but one would be new virgin queens. New queens hatch from the nest, mate, and then leave to find a place to hibernate and start a new colony the next year.

Despite multiple doses of carbon dioxide, removal of workers, and storage in a cold facility, most of the specimens were still alive when the nest was opened.

WHAT’S NEXT? The WSDA will continue to trap at least through Thanksgiving and possibly beyond, but will likely only track worker hornets. For example, our entomologists will not track down new queens if they are caught as they are unlikely to return to a nest, but will try to find a mate. Even if no other hornets are found, the WSDA will continue to catch for at least three years to show that the area is free of Asian giant hornets.

The WSDA’s Pest Control Program continues to hope to work with our northern neighbors in Canada to eradicate Asian giant hornets from the Pacific Northwest. Efforts require international collaboration, research into better detection tools, and the continued work of vigilant public observers to prevent Asian giant hornets from gaining permanent foothold here.


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