Asian giant hornet
The Asian giant hornet (Vespa mandarinia) is the largest hornet species in the world, native to Eastern Asia, including Japan, China, India, and parts of Russia. It was first identified in North America in 2019, specifically in northwestern Washington State and British Columbia, raising concerns among entomologists about its potential impact on local ecosystems, particularly honeybee populations. Known for its striking size—approximately 2 inches (5 cm) long—and aggressive behavior, the hornet has earned the nickname "murder hornet" due to its predatory nature, especially towards honeybees, which it can decimate through coordinated attacks.
Despite fears surrounding its venomous sting, experts assert that the Asian giant hornet does not pose a significant threat to humans, although it can be lethal in rare cases, particularly in Japan, where fatalities occur annually from stings. The hornets build their nests underground or in hollow trees, making them difficult to locate and eradicate. Control efforts in North America have included the use of traps and tracking technologies to manage their populations, and there have been no significant sightings in the U.S. since 2021. Interestingly, honeybees have developed defensive behaviors against these hornets, demonstrating the complex interactions within ecosystems.
Subject Terms
Asian giant hornet
The Asian giant hornet (Vespa mandarinia) is the largest hornet in the world. While native to Eastern Asia, its nests were discovered in northwestern Washington State and British Columbia in 2019. Since then, several additional Asian giant hornet nests have been eradicated, causing entomologists to fear that the ferocious hornets may be established in these areas. The Asian giant hornet was dubbed the “murder hornet” in a New York Times article because the predatory hornet viciously attacks and kills honeybees, quickly annihilating their colonies. Experts contend that Asian giant hornets pose no significant threat to humans. However, up to fifty people in Japan die each year after being stung.
Background
The Asian giant hornet is native to the temperate and tropical areas of eastern Asia, which includes the mountainous parts of Japan along with China, India, and Sri Lanka. The Asian giant hornet has also been found in far eastern areas of Russia. Known for its enormous size and distinctive coloring, the hornet’s body is nearly 2-inch (5-centimeter) long and its wingspan is about 3 inches (7.6 centimeters). It has a 0.25-inch long stinger filled with strong venom. Asian giant hornets have a yellow head, a black thorax, a yellow-and-black striped abdomen, and gray wings.
Asian giant hornets build their nests underground, usually in an abandoned rodent burrow, which makes the nests difficult to find and destroy. More rarely, these hornets build a nest in a hollow tree trunk. A nest can house more than three hundred hornets.
Like other wasps, giant hornets live in colonies with a distinct social structure. Each nest has one queen that is larger than the other hornets and lays all the eggs. Worker bees are females. Drones, males that mate with the queen, lack a stinger.
Asian giant hornets live only two to five weeks, although queens may live up to one year. Each nest produces at least one new queen each year but may produce hundreds. Queens hibernate, or overwinter, in soil until spring. When they awaken, they forage. They then search for a suitable nesting site, lay eggs, and care for the young. Some of these eggs produce female workers. Once they mature, they take over the duties of finding food for the colony and caring for young bees. Around December, drones leave the hive with a new queen. They mate with her and die. Then the cycle repeats.
Overview
Asian giant hornets were first spotted in northwestern Washington State in 2019. Entomologists are not sure how the hornets made their way from Asia to North America but speculate that their arrival is connected to international trade. Experts believe that Asian giant hornet queens may have made their way onto ships and hibernated there. When they awakened, they were in North America where they searched for nesting sites. Giant hornet queens are skilled fliers and can travel many miles per day at speeds up to 20 miles (32 kilometers) per hour to find the perfect place.
Hunting Techniques
Like other wasps, Asian giant hornets are predatory and feed mainly on caterpillars, mantises, beetles, and spiders. However, later in the season when the nest has become large, they begin killing honeybees at various hives. Their attacks are especially vicious, which is what led them to be called murder hornets. They often hunt alone, waiting outside a honeybee hive, catching one bee at a time. They use their powerful mandibles to decapitate the honeybees and tear off their legs and abdomen. They then take the protein-rich thorax (chest) back to the nest. An Asian giant hornet will continue to do this until it has killed all the honeybees in a hive.
They also hunt using a different technique, which entomologists refer to as the “slaughter phase.” With this approach, one Asian giant hornet finds a honeybee colony and marks it with pheromones, which give the hive an odor. Then the hornet goes back to its nest and returns to the honeybee hive with a group of about fifty hornets. They hover near the entrance of the hive, quickly biting to death and ripping apart any honeybee that exits. A single Asian giant hornet can behead twenty honeybees in 60 seconds. With this type of attack, they let the body parts fall to the ground instead of taking the thoraxes back to the nest. When the nest is empty, some giant hornets enter it, seizing protein-rich bee larvae and pupae to take back to their nest. Other giant hornets guard the hive while this is taking place.
Asian giant hornets do not sting people unless they are defending their nest or a food source. People who have been stung by a giant hornet describe it as being extremely painful, more painful than being stung by any other bee or wasp. The hornet’s stinger is long and sharp enough to pierce a bee suit, and a series of stings can be fatal.
Discovery
The first discoveries of Asian giant hornets in the United States occurred in northwestern Washington in December 2019. Because it was winter, the hornets people discovered were dead. A specimen was sent to an invasive-species expert and was identified as an Asian giant hornet. This sparked fears that the hornets may have already been established in the country and would soon decimate honeybee populations. Honeybees pollinate crops, so their destruction would harm human food supplies.
Luckily, Asian giant hornets have been discovered only in Washington State in the United States. Experts contend that it is unlikely that the bees will spread throughout the United States because they prefer to live in low, mountainous and forested areas. When an Asian giant hornet nest was discovered in Washington State in 2019, it was eradicated. In 2020, a team of researchers from the Washington State Department of Agriculture discovered a dead queen. They searched for and discovered additional nests, one of which had two hundred queens. Other sightings also occurred. Researchers used various methods to kill the hornets and attempt to locate their nests. They created bottle traps baited with rice cooking wine and orange juice to trap individuals. They also developed technologies, such as using dental floss to tie a tiny tracker to a hornet to locate its nest. There has not been further evidence of Asian hornets in the United States since 2021. There have been, however, sightings of one of its close relatives and another invasive species, the yellow-legged hornet. These hornets were found on the east coast of the United States in 2023, raising new alarms. In Japan, where the Asian giant hornet is commonplace, honeybees have begun to fight back. A group of honeybees will surround a giant hornet and use the motion of their wings to create enough heat to kill the hornet, a process that experts call “heat balling.”
Bibliography
“Asian Giant Hornet.” Washington State Department of Agriculture, agr.wa.gov/hornets. Accessed 13 May 2024.
Baker, Mike. “'Murder Hornets’ in the U.S.: The Rush to Stop the Asian Giant Hornet.” New York Times, 13 Nov. 2020, www.nytimes.com/2020/05/02/us/asian-giant-hornet-washington.html. Accessed 13 May 2024.
"Beekeepers Brace for Next Round with Canada’s ‘Murder Hornets’.” The Guardian, 1 Jan. 2021, www.theguardian.com/environment/2021/jan/01/beekeepers-brace-for-next-round-with-canada-murder-hornets-aoe. Accessed 13 May 2024.
Blaylock, Jeannie. “Strapping dental floss on a ‘murder hornet.’ Why that’s a big deal.” First Coast News, 27 Feb. 2021, www.firstcoastnews.com/article/life/animals/why-scientists-are-strapping-floss-on-a-murder-hornet/77-d8ed98bf-29f8-484d-8d28-b845d871067e. Accessed 15 Mar. 2021.
Embry, Paige. “Just How Dangerous Is the ‘Murder Hornet’?” Scientific American, 6 May 2020, www.scientificamerican.com/article/just-how-dangerous-is-the-murder-hornet. Accessed 15 May 2024.
Learish, Jessica. “’Murder hornets’ in America: What you need to know.” CBS News, 2 Nov. 2020, www.cbsnews.com/pictures/murder-hornet-spotted-in-the-united-states/. Accessed 15 Mar. 2021.
Levenson, Michael. “Washington State Officials Hunt for Colony of ‘Murder Hornets’.” New York Times, 3 Oct. 2020, www.nytimes.com/2020/10/03/us/murder-hornets-colony-Washington-state.html. Accessed 15 Mar. 2021.
Relyea, Kie. “’Attack of the Murder Hornets’ Showcases Whatcom and the Trace to Find these Bee Killers.” The Bellingham Herald, 21 Aug. 2021, www.bellinghamherald.com/news/local/article249107120.html. Accessed 13 May 2024.
Wulfeck, Andrew. “Relative of the 'Murder Hornet' Found Along US East Coast for First Time.” FOX Weather, 16 Aug. 2023, www.foxweather.com/earth-space/yellow-legged-hornet-ylh-vespa-velutina. Accessed 13 May 2024.