How did northern giant hornets get to Washington and British Columbia?
As with the introduction of many invasive species, there is no real way to tell how these were introduced to the Pacific Northwest. Some possibilities include international container ships, purchases shipped into the US, travelers visiting the US or returning from another country, etc. We have no information on how this pest was introduced.
Why don’t we just import Asian honey bees, since they can defend themselves from northern giant hornets?
The Eastern honey bee, Apis cerana, is one of about 12 different cavity and open-nesting honey bee species that occur in Asia. Apis cerana is widely kept by beekeepers in Asia, but in commercial operations it has been mostly replaced throughout its range by the western honey bee, Apis mellifera. The western honey bee, which is native to Europe, Africa, and western and central Asia, has been widely adopted because of its ability to produce higher honey yields than A. cerana. Other factors that make A. cerana difficult to manage for large-scale commercial pollination and honey production include seasonal migration, and a tendency to “abscond” (abandon their hive) when disturbed.
There are other reasons to be wary of importing Apis cerana. Although Apis cerana has effective behavioral defenses against the Asian giant hornet, it is also host to multiple parasitic mites that can destroy colonies of A. mellifera. One of these, Tropilaelaps clareae, has not yet reached Europe or the Americas. Many entomologists believe that Tropilaelaps could be more devastating to US honey bees than the Varroa mite, and annual nationwide monitoring of US honey bee populations to prevent establishment of this parasite is a high priority of USDA-APHIS. Importing A. cerana might also provide a pathway for bee viruses to enter the US, creating a high risk to both managed Apis mellifera populations and native bee species. Finally, Apis cerana itself could be problematic. After being introduced to Australia and Papua New Guinea, it became highly invasive and displaced native bee species. All efforts to suppress it have so far failed.
Intentionally introducing A. cerana would pose a huge risk to US agriculture and native bees, and is not currently a viable solution to managing northern giant hornets even if they become established. It is also illegal under federal law. As a final note, remember that beekeepers still raise western honey bees in places where northern giant hornet is native! It takes more resources, but the industry is viable.
There are other reasons to be wary of importing Apis cerana. Although Apis cerana has effective behavioral defenses against the Asian giant hornet, it is also host to multiple parasitic mites that can destroy colonies of A. mellifera. One of these, Tropilaelaps clareae, has not yet reached Europe or the Americas. Many entomologists believe that Tropilaelaps could be more devastating to US honey bees than the Varroa mite, and annual nationwide monitoring of US honey bee populations to prevent establishment of this parasite is a high priority of USDA-APHIS. Importing A. cerana might also provide a pathway for bee viruses to enter the US, creating a high risk to both managed Apis mellifera populations and native bee species. Finally, Apis cerana itself could be problematic. After being introduced to Australia and Papua New Guinea, it became highly invasive and displaced native bee species. All efforts to suppress it have so far failed.
Intentionally introducing A. cerana would pose a huge risk to US agriculture and native bees, and is not currently a viable solution to managing northern giant hornets even if they become established. It is also illegal under federal law. As a final note, remember that beekeepers still raise western honey bees in places where northern giant hornet is native! It takes more resources, but the industry is viable.
Can commercial hornet traps be used to trap northern giant hornets?
No. The holes in commercially available hornet traps are too small for the northern giant hornets to enter and will not be effective for trapping these hornets. We have provided citizen scientist trapping instructions on our website.
What types of traps are effective for trapping northern giant hornets?
Research shows that various types of traps have been effective for northern giant hornets in their native range. Trapping for hornets in Washington State begins in July and goes through November, when hornet workers are most active. Trapping outside of this window is highly unlikely to catch the hornets and will unnecessarily kill other insects. People in Washington State can build a homemade trap and report hornet catches to WSDA.
If you do not live within Washington State, please contact your state or province department of agriculture for guidance on trapping for northern giant hornets.
If you do not live within Washington State, please contact your state or province department of agriculture for guidance on trapping for northern giant hornets.
Can praying mantis control or kill northern giant hornets?
A popular and gruesome video on the internet shows a large praying mantis attacking and quickly consuming an northern giant hornet. This video, plus the predatory reputation of mantises in general, has many people wondering why we can’t just use this natural control to deal with the hornets. There are a few reasons why this is not likely to be a useful broad strategy. First, the hornet in the video was anaesthetized before filming! While it is certainly possible that a mantis could kill an NGH in the field, it is also likely that the hornet would kill the mantis. In fact, praying mantises are a well-documented food source for the northern giant hornet in their native range.
Even if mantises were more effective predators of northern giant hornets, it is very difficult to maintain high enough populations of general predators to control pest insects. Consider that each hornet nest might have a few hundred active workers at maximum colony size, and that there are likely multiple colonies active in the same area at the same time. A praying mantis can only eat so many insects, and they would have to be in the right place at the right time to catch one. There is no evidence that they would preferentially seek hornets or hornet nests. Other aspects of their biology that make them unlikely to control the hornet if it becomes established include a slow reproductive rate for the mantises and the fact that they will eat any insect they happen upon - in fact, they seem to prefer grasshoppers and related insects. If that rare hornet-praying mantis encounter even happens, they might already be satiated from eating other insects - including honey bees! The presence of praying mantises also changes honey bee behavior; honey bees will avoid foraging when they see praying mantises. Saturating the landscape with praying mantises (which would require an industrial insect-rearing facility) would likely have negative impacts on managed pollinators and many native insect species.
The two large praying mantises in Washington State are introduced species, and while they are an interesting and acceptable presence in our gardens, they aren’t effective or specialized enough to control any species of insect – including hornets – at a large scale. While you’re here, consider learning about our native mantis, which is uncommon and difficult to find.
Even if mantises were more effective predators of northern giant hornets, it is very difficult to maintain high enough populations of general predators to control pest insects. Consider that each hornet nest might have a few hundred active workers at maximum colony size, and that there are likely multiple colonies active in the same area at the same time. A praying mantis can only eat so many insects, and they would have to be in the right place at the right time to catch one. There is no evidence that they would preferentially seek hornets or hornet nests. Other aspects of their biology that make them unlikely to control the hornet if it becomes established include a slow reproductive rate for the mantises and the fact that they will eat any insect they happen upon - in fact, they seem to prefer grasshoppers and related insects. If that rare hornet-praying mantis encounter even happens, they might already be satiated from eating other insects - including honey bees! The presence of praying mantises also changes honey bee behavior; honey bees will avoid foraging when they see praying mantises. Saturating the landscape with praying mantises (which would require an industrial insect-rearing facility) would likely have negative impacts on managed pollinators and many native insect species.
The two large praying mantises in Washington State are introduced species, and while they are an interesting and acceptable presence in our gardens, they aren’t effective or specialized enough to control any species of insect – including hornets – at a large scale. While you’re here, consider learning about our native mantis, which is uncommon and difficult to find.
How do I report an northern giant hornet sighting?
If seen in Washington:
Please report any suspected northern giant hornet sighting to the Washington State Department of Agriculture. You can do so easily online at agr.wa.gov/hornets. You can also email hornets@agr.wa.gov or even call us at 1-800-443-6684. If you are able to obtain a photograph of the suspected hornet, that will dramatically increase our ability to verify your report. If you find a specimen, photograph it and send the photo to us. Put the specimen in the freezer in a baggie until you hear whether it is an northern giant hornet or not.
If seen in another state or province:
Please report to the invasive species managers in your area, such as a department of agriculture or invasive species council. We are unable to assist with northern giant hornet detections outside of Washington State.
Please report any suspected northern giant hornet sighting to the Washington State Department of Agriculture. You can do so easily online at agr.wa.gov/hornets. You can also email hornets@agr.wa.gov or even call us at 1-800-443-6684. If you are able to obtain a photograph of the suspected hornet, that will dramatically increase our ability to verify your report. If you find a specimen, photograph it and send the photo to us. Put the specimen in the freezer in a baggie until you hear whether it is an northern giant hornet or not.
If seen in another state or province:
Please report to the invasive species managers in your area, such as a department of agriculture or invasive species council. We are unable to assist with northern giant hornet detections outside of Washington State.
Will beekeeping suits protect me from northern giant hornet?
No. Northern giant hornets have stingers which are longer than those that honey bees have, meaning hornets can sting through typical beekeeping attire. The hornets can sting repeatedly and their sting is more dangerous than that of local bees and wasps.
USDA recommends suits made for protection from hornets, rather than from bees. WSDA cannot give recommendations on which suits may protect you from hornet stings.
USDA recommends suits made for protection from hornets, rather than from bees. WSDA cannot give recommendations on which suits may protect you from hornet stings.
Where have northern giant hornets been found?
In North America, northern giant hornets have only been detected in British Columbia and Whatcom County in Washington State.
You can find complete detection data on our website.
What is WSDA doing to respond to the introduction of northern giant hornets in Washington?
WSDA has a team of experienced entomologists in our Pest Program collaborating with federal and international experts. We are creating a plan to trap, track, and eradicate northern giant hornet in Washington, including working with Canada to ensure that populations on both sides of the border are managed.
The basic plan includes several months of trapping. Summer and fall trapping will include trapping hornets live, tagging them, and tracking them back to their colony. Once a colony is discovered, the colony will be eradicated.
WSDA will continue trapping and eradicating the hornets until either a population becomes permanently established or there are three years without a confirmed hornet sighting.
WSDA plans to work extensively with the public to provide outreach and education about the hornets as well as to encourage the public to document and report hornet sightings. However, northern giant hornets are dangerous and WSDA encourages everyone to avoid approaching them.