The 2-inch long Asian giant hornets have landed in the US for the first time, spotted on the west coast.
Multiple stings are deadly to humans and in their "slaughter phase" the hornets destroy honeybees, whose bodies they feed to their young.
Scientists are now on a hunt for the hornets, hoping to eradicate the species before they wipe out US bees.
Though they typically avoid people, in Asia, "murder hornet" stings are thought to cause as many as 50 human fatalities a year, according to the New York Times.
The hornets made their first North American appearance in August 2019, in British Columbia, Canada. Months later, in December 2019, the flying insects were reported south of the border, in Washington State.
Washington State University (WSU) are unsure how or when the hornet first arrived in North America, but beekeepers in the region have reported gruesome hive deaths in recent months. Scientists are bracing for further emergence of the species, which begins its life cycle in spring.
The hornets are "shockingly large", said Todd Murray, a WSU scientist and invasive species specialist. "It's a health hazard, and more importantly, a significant predator of honeybees."
The insects, roughly the size of a matchbox, have large yellow-orange heads, prominent black eyes, and a black and yellow striped abdomen.
"They're like something out of a monster cartoon with this huge yellow-orange face," said Susan Cobey, a bee breeder with WSU entomology department in a press release.
The Asian giant hornet's life cycle begins in April, when queens come out of hibernation, and begin to feed and seek out subterranean dens to build their nests. Once their habitats are built in the summer and autumn months, worker hornets are sent to find food.
With their sharp, spiked mandibles, the hornets decapitate honeybees, using the bodies to feed their young. The hornets can destroy a honeybee hive in a matter of hours.