You’ve probably learned about the Asian giant hornet by its nickname, the “murder hornet” from the news. Asian giant hornets get their intimidating nickname from killing honey bees. Unfortunately, this nickname causes fear that these hornets will target human too. But, Asian giant hornets aren’t usually aggressive toward us. Unless we stumble upon and disturb their nest and food source, these hornets usually won’t attack humans or pets.
When the hornets attack, they use their stinger and they can spray their toxic venom. The sting causes a sharp pain. In addition, the venom of Asian giant hornets is toxic and dangerous. Multiple stings can trigger anaphylactic shock or even worse, it can cause death.
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Asian Giant Hornets
Not all honey bees are susceptible to this ferocious predator. One honey bee species, Apis cerana (Asian honeybees), has a fascinating defensive strategy to fight this Asian giant hornet. This strategy is to trap, bake, and kill the hornet by the formation of a hot defensive bee ball (with the temperature around 117˚F).
Why 117˚? Asian honey bees can survive temperatures up to 118˚F, but the giant hornet can only tolerate heat up to 115˚F. So the Asian honey bees use this adaptive trait as an advantage to gain a victory during the battle against the hornet. This risky strategy pays off well for the Asian honey bees allowing them to save their colony. If you want to learn more about this strategy, you can watch this video.
What is the Asian Giant Hornet?
How to identify Asian giant hornet? One quick way to identify Asian giant hornets is by their huge size (around 1.5–2.0 inches long), compared to the size of honey bee workers (0.4–0.6 inch. long) or the yellow jacket wasp (0.5–0.75 inch. long).
The scientific name of the Asian giant hornet is Vespa mandarinia. The queen of the Asian giant hornet is the world’s largest hornet. The queen size is up to 2.0 inch. long, whereas the workers can grow to 1.5 inches in length. Their abdomen has black and yellow stripes. Their head is yellow, and their eyes are big, reminding many of Spiderman’s eyes.
Where are Asian Giant Hornets Commonly Found?
The Asian giant hornet is native to East Asia, South Asia, the continental portion of Southeast Asia, and some regions of Russian Far East. Their preferred habitats in Asia are forested regions that are similar to the forested regions of the Pacific Northwest.
In 2019, these hornets made their first appearance in the Pacific Northwest (British Columbia and northwest of Washington State). Since last year, entomologists at Washington State University and Washington State Department of Agriculture have been working on trying to trap, locate, and eliminate any Asian giant hornet nests.
So far, there has been no reports about these hornets in other parts of the U.S. So, for example, if you live in the Midwestern area of the U.S. and find similar looking hornets, they are most likely European hornets (around 1.0–1.4 inch. long) or cicada killer (around 0.6–2.0 inch. long).
What is a Hornet?
A hornet is a large wasp (usually more than 1.0 inch. long). Hornets belong to a large group of insects in the Hymenoptera order that also include bees, wasps, ants, and sawflies. Most of these hymenopteran insects are beneficial insects for us. They help us to control agricultural pests or pollinate agricultural crops. Some are predators of other insects (including agricultural pests) and spiders.
How Do the Hornets Attack Honey bees?
The Asian giant hornets live in large colonies, and they always need a large amount of food. Therefore, they forage susceptible honeybees as their prey since the bees live in large colonies too. A hornet hunts an individual honey bee worker to find the honey bee’s hive location and mark the hive with a marking pheromone. A marking pheromone is a chemical produced by insects to mark their territory.
Using the marking pheromone, the hornet recruits its nest mates to come to the honey bee nest. Soon after, the number of hornets attacking the bees increase and the bees can’t win the battle. These hornets then kill the honey bees by decapitating them and use the brood of the bees to feed their own offspring.
How Do the Asian Honey bees Defend Themselves from the Hornets?
Asian honey bees (A. cerana) develop adaptive responses to the marking pheromone of the Asian giant hornet. The bees detect the marking pheromone of the hornet and retreat into their hives. Inside the hives, the honey bees fight the hornet by forming a ball, trapping, and killing the hornet inside the bee ball.
These bees don’t use their stinger to kill the hornet. Instead, they vibrate as a group. The vibration causes heat that cooks the hornet. In addition, carbon dioxide level inside the ball increases. As a result, the hornet is killed. Scientists refer this defensive strategy by the Asian honey bees as “heat-balling”.
European honey bees (Apis mellifera) introduced in the early 1600s are common in North America. With local wasp or hornet species abundant in their area, the European honey bees show some defensive responses. These defensive responses include swarming at the opening of the hive, flying at the wasp to scare the wasps, and heat-balling.
Fewer worker bees are involved in the formation of the hot bee balls for European honeybees than for Asian bees. The temperature of the hot bee balls of the European honey bees is also lower than the bee balls of Asian honeybees. In addition, the European honey bees don’t show a similar response to the Asian giant hornet pheromone as the Asian bees. This lack of response by the European honey bees may be due to the lack of exposure to the Asian giant hornets, making the bees more susceptible to them.
How Do You Avoid Getting Attacked by the Asian Giant Hornets?
Now, what if you are out in the woods and you accidentally come near a hornet nest, and notice that it might be an Asian giant hornet nest. How do you avoid an attack?
- Don’t panic.
- DON’T try to fight or kill the hornet.
- Try to move away from it and run fast.
- If possible, go inside your car.
- If you get stung for multiple times, seek medical attention.
You may find additional information about Asian giant hornets from Washington State University Extension Website and if you suspect that you see them in your area, contact your state’s department of agriculture.
References
Additional Information on Asian Giant Hornet | Whatcom Ag Monthly | Washington State University. (n.d.). Whatcom Ag Monthly. Retrieved May 5, 2020, from https://extension.wsu.edu/wam/asian-giant-hornet-f...
Asian Giant Hornets. (n.d.). Penn State Extension. Retrieved May 7, 2020, from https://extension.psu.edu/asian-giant-hornets.
Baker, M. (2020, May 2). Tracking the ‘Murder Hornet’: A Deadly Pest Has Reached North America. The New York Times. https://www.nytimes.com/2020/05/02/us/asian-giant-...
Baracchi, D., Cusseau, G., Pradella, D., & Turillazzi, S. (2010). Defence reactions of Apis mellifera ligustica against attacks from the European hornet Vespa crabro. Ethology Ecology & Evolution, 22(3), 281-294.
Denis, J. S. (2020, May 3). Asian giant hornets - aka “murder hornets” - expected back in B.C. British Columbia. https://bc.ctvnews.ca/asian-giant-hornets-aka-murd...
Fox, A. (n.d.). No, Americans Do Not Need to Panic About “Murder Hornets.” Smithsonian Magazine. Retrieved May 6, 2020, from https://www.smithsonianmag.com/smart-news/invasion...
Hornets | Washington State Department of Agriculture. (n.d.). Agr.Wa.Gov. Retrieved May 5, 2020, from https://agr.wa.gov/departments/insects-pests-and-w...
Ken, T., Hepburn, H., Radloff, S., Yusheng, Y., Yiqiu, L., Danyin, Z., & Neumann, P. (2005). Heat-balling wasps by honeybees. Naturwissenschaften, 92(10), 492-495.
McClenaghan, B., Schlaf, M., Geddes, M., Mazza, J., Pitman, G., McCallum, K., . . . Otis, G. W. (2019). Behavioral responses of honey bees, Apis cerana and Apis mellifera, to Vespa mandarinia marking and alarm pheromones. Journal of Apicultural Research, 58(1), 141-148.
Sugahara, M., & Sakamoto, F. (2009). Heat and carbon dioxide generated by honeybees jointly act to kill hornets. Naturwissenschaften, 96(9), 1133-1136.
Truscott, S., Agricultural, C. of, Human, & Sciences, N. R. (2020, April 6). WSU scientists enlist citizens in hunt for giant, bee-killing hornet | WSU Insider | Washington State University. WSU Insider. https://news.wsu.edu/2020/04/06/wsu-scientists-enl...
