Giant Asian Hornet (Vespa mandarinia)
Also known as murder hornets or sparrow wasps
Credit: Yasunori Koide – Wikimedia Commons
Giant Asian Hornets are well named as the world’s largest hornet. A queen’s body length can grow to exceed 5 cm/2 inches (width of a driver’s licence), with a wingspan that can exceed 7.6 cm/3 inches (length of a driver’s licence). Males and female workers look very similar but are smaller at 3.5 to 3.9 cm/1.5 inches in body length. Their colour is distinctive - you should look for orange-yellow heads, a black or dark brown thorax, and striped abdomens – with alternated bands of orange-yellow and black or orange-yellow and brown. The stinger region is entirely yellow. In North America, there are several native and invasive insects that are commonly confused with the giant Asian hornet including the European hornet, eastern cicada killer and giant European hornet.
Giant Asian hornet is native to Southern Asia, from India through China, into Japan and Korea. They are known for inhabiting the lower altitude forest and avoiding large plains and high-altitude regions. They have been found in the Nanaimo, BC area (September 2019) as well as south into Washington state (December 2019). At this time, there is no information suggesting that the giant Asian hornet will spread over the Rocky Mountains without human assisted movement. More research is needed to accurately map the potential climatic ranges where the giant Asian hornet could survive.
Human Health Impacts
Giant Asian hornet, like many native wasps, hornets, and bees do contain venom in their stingers. They are not typically aggressive toward humans unless provoked. If nests or insects are disturbed, these hornets will sting humans.
If provoked, the giant Asian hornets can sting multiple times causing swelling with each sting. If a person were to disturb a nest and be stung many times, it could have serious health consequences. If a person is allergic to hornet venom, then giant Asian hornets could cause an allergic reaction and possibly death. As we know that giant Asian hornets can cause multiple painful stings, it is important to take appropriate precautions when coming across a nest or habitat where these hornets live. Please call professional pest control organizations or your local beekeeping organization to dispose of these species correctly, because giant Asian hornets can be extremely territorial and highly aggressive when their nest is disturbed.
Giant Asian hornets can be compared to the lions and great white sharks of the insect world. They are carnivores that kill other insects for food. Unfortunately, they can have a large impact to honeybee populations and can cause serious damage to a honeybee hive. A colony of Giant Asian hornets can kill up to 30,000 bees in a few hours. The destruction of bee populations can have large impacts to the environment and food production industry because of bee’s important role as pollinators.
Giant Asian hornets can have large impacts to bee populations which affects both native plants, crop yields, and the honey industry. As well as impacting the food industry, hikers and other recreational activities can be affected by these hornets. If the nests are disturbed, giant Asian hornets can become aggressive and territorial, chasing hikers away from trails.
A recent European study analyzed the cost of fighting the invasion of the Asian hornet - which basically consists of the cost of nest destruction. The research team studied information about the companies providing the services in the nest destruction, extrapolated the cost of nest destruction spatially and modelled the potential distribution of the invasive and at this time, the calculations show that the estimated yearly costs for eradication would be $44.6 million Canadian for three European countries (Morgane Barbet-Massin et al, The economic cost of control of the invasive yellow-legged Asian hornet, NeoBiota (2020). DOI: 10.3897/neobiota.55.38550).
Should I be worried? Why are they called murder hornets?
The giant Asian hornet kills bees, so perhaps this is where the nickname originated. In most cases, when a human is stung it is unpleasant but not fatal. Human life is only at risk when there is an allergy to the venom or if a hive is disturbed.
Where do they live?
These hornets create nests in burrows underground; however, they can also be found in large fallen tree cavities, abandoned outbuildings, and under foundations.
How did they get to North America?
Currently it is unknown how the Nanaimo, BC population got into Canada. There is some speculation that a female “Princess or Queen” could have been imported to Canada via outdoor terracotta/landscaping pots. Female giant Asian hornets overwinter in underground chambers and cling to the top of that chamber. However, sometimes they can cling to the bottom surface of a pots or stones that is sitting on the ground, like their underground chambers. Another possibility is through human movement or accidental human movement. For example, invasive hornets were transported by tourists from France to the United Kingdom in a person's camping gear.
Can they survive Canada’s cold climate?
The establishment of giant Asian hornet into Canada is unlikely and the population in Nanaimo, BC was thought to be a temporary and not permanent colony. There are conflicting results from real-time data and climate modeling describing the suitability of establishing a permanent population. More information is needed to accurately determine the potential risk for Canada to host a permanent population.
What can be done to stop them?
Early detection is the best way to prevent the spread of invasive species. By reporting sighting of giant Asian hornets’ beekeepers and other pest removal organizations can remove and properly destroy growing nests.
How do I report a sighting of this invasive species?
In Ontario, report to eddmaps.org/Ontario or the Invading Species Hotline on 1-800-563-7711. Check our website for all other provinces: https://www.invasivespeciescentre.ca/Report-A-Sighting. Provide a photo if it’s possible to take it safely.
For more info or to arrange a media interview, please contact Deb Sparks on email@example.com or (705) 255-8301.
Credit: Thomas Brown–flickr