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  5. Asian giant hornets in North America—a reality check

Asian giant hornets in North America—a reality check

Q & A with bee and wasp expert Tom Onuferko

The discovery of Asian giant hornets (dubbed “murder” hornets) in British Columbia and Washington State have recently made headlines. The arrival of spring has enticed folks outside, and sights of insects resembling hornets may be stirring up undue concern.

We asked our Beaty post-doctoral fellow Tom Onuferko, Ph. D., (whose research specializes in native bees and wasps) to give us the scoop on these winged newsmakers.

Q: What are Asian giant hornets and why are they in the news?
A: Asian giant hornets are a species of true hornet (genus Vespa), namely V. mandarinia. They occur naturally in much of Asia where they play a vital role as predators of other insects in their native ecosystems.

Recent reports of this species in British Columbia and the American Pacific Northwest has led to concern they may become established in North America. They are large insects (with a wingspan of around 3 inches, 7.5 cm), capable of delivering a painful sting, and feed on honeybees and other insects.

Q: Why are they referred to as “murder hornets” in the media and should I be concerned about them?
A: Not really. The term “murder hornets” is attention-grabbing but misleading and overstates their threat.

Asian giant hornets can deliver a very painful sting if they perceive themselves or their colony to be under threat, and should therefore be avoided. Stings, especially from multiple individuals, can be dangerous, but even in their native range, human fatalities are rare. Concerns about their establishment in North America have more to do about their impact on the economy and natural environment rather than on human health.

© Tom Onuferko


European hornet (female), collected by Tom Onuferko in the Niagara peninsula, spring 2012. The Asian giant hornet and European hornet each have distinct bands—the yellow bands in the European hornet are broader in the posterior part, with distinct notches that appear as dark “spots”. The Asian giant hornet does not have these “spots”.

Q. Are reports of sightings encouraged?
Yes, if you are in the areas where the species has been observed in North America—in a few localities in British Columbia and Washington State. However, it is important that any reports be confirmed before any attempts at eradication are made. Certain beneficial, solitary, and usually docile native wasps such as the cicada killer (Sphecius speciosus) have unfortunately been confused with hornets and killed. It is a tragedy when misinformation leads to unjustified fear and destruction of our native wildlife.

Q: Are Asian giant hornets bad for bees and beekeepers?
A: Possibly. Canada is home to about 900 species of bees, the vast majority of which are native to the country, and it is unknown what effect the introduction of Asian giant hornets will have on them.

Asian giant hornets have been known to decimate colonies of honeybees, which is a food source for them. Honeybees are also an exotic species in North America, where they have no natural predators. As such, they may be especially vulnerable to predation by these hornets. Keep in mind that honeybees themselves compete with and displace native species, especially other bees. So a decline in honeybee populations would impact economic activity from honey production and pollination of some crops, but their losses would not negatively impact our native ecosystems.

Q: What would happen if Asian giant hornets became established in North America?
A: The introduction of any exotic species can wreak havoc on native ecosystems. Asian giant hornets are among the latest in a long list of organisms that have made their way to new environments, presumably because of human activity. Their affinity for honeybees as food is concerning for some apiculturists, but it is difficult to predict what effect the hornets would have on native wildlife. At the very least, these predators would compete with and potentially displace other insect predators.

Q: I live in Eastern Canada and think I might have seen an Asian giant hornet. Is this possible?
A: It’s extremely unlikely. If you live anywhere except in a small area of southwestern  British Columbia or Washington State, you will not have come across this species in the wild in North America.

That said, some species found in Eastern Canada might be mistaken for the Asian giant hornet. The most likely candidate is the European hornet (Vespa crabro). As a true hornet, this species was introduced to New York state in the 1800s. It has since become established across much of Eastern North America, including southern Ontario. Their presence has led to false reports of the Asian giant hornet in areas where it almost certainly does not occur.

Interestingly, despite the presence of European hornets in North America for around 200 years, the species has not managed to expand its range to the west coast. So even if Asian giant hornets were to establish themselves in western North America, their spread eastward would not be assured and could take a very long time.

Other native species may also be confused with the Asian hornet. They are:

  • The bald-faced hornet (Dolichovespula maculata), which is native to North America, is not a true hornet but a type of large yellowjacket (one that is mostly black). It is thought of as a hornet because it is larger than some of the other common yellowjackets.
  • The largest native wasp in Eastern Canada is a solitary species that preys on cicadas – the cicada killer (Sphecius speciosus). It has also been confused with hornets, but is more closely related to bees than hornets. Although capable of stinging in defense, this wasp is docile and helps to keep cicada numbers under control.

Final thought
It is important to monitor for invasive species and this requires knowledge of native species in Canada as well as species from abroad. Museums such as the Canadian Museum of Nature offer both the expertise of taxonomists who can differentiate species, as well as scientific collections that can be consulted as the evidence of what exists and where it is found.