Local beekeepers found and safely got rid of a greater banded hornet nest at Inarajan Elementary School.
Christopher Rosario, local apiarist and member of the Guam Beekeepers Association, got the call on July 3. At the school, he found a nest built into the cavity of a tree just feet from the school building.
"This is very typical," he said of the nest's location. "Hornets typically nest 10 feet or below – they're called subterranean species."
Rosario, who provides this service for free alongside fellow beekeepers, is typically called upon to eradicate colonies.
Entomologists at the College of Natural and Applied Sciences at the University of Guam reported in July 2016 one of the initial sightings of the Vespa tropica, also known as the greater banded hornet, on the island. They are large and aggressive, which make them a possible health hazard to individuals with allergies to bees and wasps, as well as children and the elderly, according to UOG.
"I take it upon myself to eradicate these types of species, because they are dangerous to the public health and dangerous to our pollinators," said Rosario, who also owns his own honey business, RoCo Honey.
The greater banded hornet is an invasive species from Asia that prey on local bees. Officials said they were first spotted locally in 2016. They've been observed killing entire colonies of bees. A few years ago, a colony swarmed local firefighters who were rescuing a stranded dog in Tamuning and unknowingly came across the nest in the course of the rescue attempt.
Rosario said he's done a dozen eradications of nests found by residents in trees, bushes, office or household closets, and even inside concrete walls.
"Wherever there's a cavity ... that's sheltered and close to the ground, they'll build their nest," he said. "That rescue a few years ago where the firefighters got swarmed, that nest was in a small crevice on the side of the cliff where they were rappelling down, and ... the chains of love (vines) had grown over it so they couldn't see it."
Rosario said to eradicate the colony, he wraps the nest with painters plastic, and sticks in a fumigant, killing the adults.
"Now after getting rid of the adults, we went into the tree and started taking out the larvae or eggs ... and whatever was left inside the tree we burned," he said.
Once the nest was cleared, they were able to see the tree cavity was more than 2 feet tall and nearly as wide.
"In the pictures, the tree doesn't look that big ... but once we got everything out I could fit my arm in there," he said.
The hornets are found in China, Japan, Malaysia, Hong Kong, Singapore, India and the Philippines.
They raid the nests of other species to take larvae back to their own nest to feed their larvae. The greater banded hornet has a distinct, bright yellow band around its abdomen. They build their nests in hollow trees and other protected areas or underground. Queens are about 30mm in size and the workers average 24-26mm, which is slightly larger than the diameter of a quarter.