WSDA Takes Hornet Nest Removal to New Heights

In late September, WSDA’s Pest Program removed the third Asian giant hornet (Vespa mandarinia) nest of 2021, making it the fourth nest removed since the invasive hornet was first detected in Washington in December 2019. All of the nests have been in the same general area east of Blaine.

Most research on these hornets suggests that they normally nest in the ground and more rarely in trees. But so far, 100 percent of nests found in Washington have been in tree cavities. The entrance to this latest nest was over 15 feet above the ground. A thermal-imaging camera showed the nest itself was below the nest entrance.

The challenge posed by working on a nest so high up was compounded by the fact that the nest was also surrounded by dense trees and vegetation – especially blackberry patches as much as eight feet tall. The team of entomologists and others from the pest program had to use some new tools to eradicate this nest, including a rented bucket lift to raise them over the bulk of the vegetation so they could work safely at the nest entrance.

Just as in the other nest removals, once at the entrance, the team sealed up the tree and vacuumed most of the hornets out before sealing the entrance.

In addition to the height of the nest, it was also in a decaying alder tree. This made it risky to safely cut the tree down. A trail steward from the Department of Natural Resources was able to help. Wearing a bulky hornet suit, he cut the tree so it dropped right on target. Once the tree was down, he cut it into sections and split the tree open so the team could finish collecting the remaining hornets and the nest.