“Murder Hornets” in the U.S. by Lucia Butler

Vespa mandarinia. (Courtesy of Creative Commons.)

The Asian giant hornet (Vespa mandarinia), also known as the “murder hornet”, was found near Blaine, Washington, in December, 2019. Since then, they have also been found in Bellingham, Washington, and British Columbia, Canada. They are the world’s largest wasps, ranging from 1.5 to 2 inches in length, with quarter-inch long stingers that contain toxic venom potentially lethal to humans. 50 stings or less from an Asian giant hornet can kill an individual due to kidney damage. Those allergic to bees or wasps can experience a sometimes fatal anaphylactic shock after being stung only once.

An Asian giant hornet trapped near Birch Bay in Whatcom County, Washington. (Courtesy of Washington State Department of Agriculture.)

Asian giant hornets are native to East Asia and Japan, but how they arrived in the U.S. is still unknown; it is hypothesized that they were accidentally brought to the country in a shipping container. On average, the wasps kill 30 to 50 people in Japan each year; however, they mainly attack only when their hives are approached. The hornets’ stingers, which contain a pernicious enzyme mixture and neurotoxin, can pierce through a beekeeper’s suit or other protective clothing. Recently, when a beekeeper/entomologist attempted to remove an Asian giant hornet hive in Vancouver Island, he was stung seven times through his protective clothing and beekeeper’s suit. Shunichi Makino, of Japan’s Forestry and Forest Products Research Institute, describes the giant hornet sting as similar to being “stabbed by a red-hot needle”. 

The name “murder hornet” was coined on social media and has naturally engendered fear of this insect. While Asian giant hornets look very similar to the European hornet (Vespa crabro), they are generally more aggressive and dangerous. Asian murder hornets are just as dangerous as Africanized honeybees, known as “killer bees”, hybrids of the western honey bee (Apis mellifera). These bees are known to chase people up to a quarter of a mile and sting victims approximately ten times more than the typical European hornet.

Asian giant hornets are not only a threat to humans but to the U.S.’s already-declining honey bee populations as well. The hornets eat many types of insects, but they favor bees especially: they are known to travel half a dozen miles or more from their hive in search of food and can easily wipe out entire bee colonies. Within a beehive, a small group of these hornets can annihilate an entire colony within as little as 90 minutes. They then live in the hive for a week or more and feed on bee larvae and pupae. Usually, the queen Asian giant hornet and other adult hornets will regurgitate food for their young. Where they are not feeding on bees, Asian giant hornets usually build their nests underground, building new hives in mid-to-late October.

Luckily, Japanese honeybees have long co-existed with these hornets and have developed their own defense mechanisms. They are known to swarm around Asian giant hornets by creating a “bee ball” that suffocates and “cooks” the hornets to death with temperatures over 115 degrees Fahrenheit. The below image shows an experiment examining this defensive method.

(Courtesy of Wikimedia Commons.)

Currently, researchers are engaging in efforts to contain the U.S.’s Asian giant hornet populations, especially since the hornets are known to be most destructive during the late summer and early fall. Their threat to North America’s natural ecosystems is evident; the Washington State Department of Agriculture states: “If it becomes established, this hornet will have negative impacts on the environment, economy, and public health of the Washington State.” Scientists are using radio trackers to trace numerous giant hornets back to their hives in anticipation of eliminating their risk to the state’s pre-existing ecological community.