Asian Giant Hornet

Samantha Muirhead, Provincial Apiculturist & Alexandra Panasiuk, Lead Apiculture Inspector

Although first detected in British Columbia (BC) and Washington State (WA) in 2019, the Asian Giant Hornet (AGH) Vespa mandarinia, nicknamed the “Murder Hornet”, was one of the top 10 news headlines around Canada and the United States in 2020. Native to the temperate and to some sub-tropical regions of eastern parts of Russia and South East Asia, the AGH is the largest of the hornet species in the world. In contrast to our largest native wasp species in Alberta, the banded horntail (2- 4 cm), AGH workers range in length from 3.5 to 4 cm and queens up to 5 cm.

The AGH has a number of unique life history traits that make it an exceptionally concerning invasive species. The queen is the only member of the AGH colony that survives the winter and emerges in the spring.

If the queen is mated, she will seek a suitable location for a nest and will begin laying worker eggs. At this time, she is responsible for all nest duties, including foraging, until there are enough workers to take on the responsibilities outside of the colony. At this point, the queen will become nest-bound where her sole responsibility is laying eggs.

As the number of workers in the colony steadily increases and fall approaches, the queen will begin producing males and next season’s queens (over 200 queens per nest). This phase is where honey bee colonies are most vulnerable to mass attacks from AGH and when beekeepers need to be most concerned. During these attacks, one hornet can kill one honey bee every 1-14 seconds by decapitating it. Remarkably, they are not interested in feeding on adult honey bees, their primary goal is to overthrow the colony for its protein rich larvae, which can happen in as little as 1-6 hours. AGH then occupies the nest for up to 10 days where they collect the honey bee larvae to feed the next generation of queens and males. Workers and males die before overwintering takes place, so queens must mate at this time to reproduce the following season. Potentially hundreds of queens, whether mated or not, disperse from the mother nest to find a spot to overwinter in soil, rotting wood, or piles of straw. In the spring, if the queen was successfully mated in the previous year, the cycle will begin again.

In North America, the AGH is believed to have been unintentionally introduced from shipping containers coming from their native locations, but the exact mode of entry is still unknown.

In August 2019, AGH was found on Vancouver Island in Nanaimo, BC. After collaboration with local beekeeper groups and the BC government, a single nest was found and successfully eradicated. It is believed that the nest was eradicated before the emergence of queens, but as a precaution, a surveillance program was developed in the chance that a few had dispersed.

To date, no AGHs have been found on Vancouver Island but surveillance will continue this year. Additionally, in late 2019, one AGH specimen was found in lower mainland BC and another in WA, USA, approximately 2km south of the Canada-US border. Although the specimens were found relatively close to each other, it was determined that they were not from the same nest. Because these specimens were found so late in the year, and the nests were never located, the queens most likely had an opportunity to leave the nests to overwinter in other locations.

As a result, surveillance programs were established in both WA and BC in 2020. Scientists in WA were able to successfully track an AGH worker back to its nest where it is was swiftly eradicated. In 2020, thanks to public reports, 5 AGH were found in lower mainland BC, one of which was detected outside the surveillance area. Unfortunately, no AGH nests were located. This means not only will surveillance continue but the surveillance area will have to be expanded in the spring of 2021.

The Bee Health Assurance Team (BHAT) has fielded many calls and emails from the general public reporting sightings of this predator. Thankfully, these reports all turned out to be “look-alikes”, including bumble bees, elm sawflies, banded horntail wasps, yellow jackets, and bald-face hornets.

Public engagement and awareness is vital to early detection and eradication of AGH if it is introduced into Alberta. Although approximately 50,000 + colonies move between BC and Alberta annually, this is not considered a risk for introduction of AGH into the province. Fortunately, AGH does not nest in honeybee colonies, and in order for a colony to establish, a queen is required. However, it is important to familiarize yourself with native species in Alberta, such as those listed above. As mentioned in BC, even with surveillance programs in place, all AGH findings were reported by the public.

For more information on the biology of the AGH, the United States Department of Agriculture has created a document called “New Pest Response Guidelines, Vespa mandarinia, Asian giant hornet.” This can be found online.

If you see or suspect an insect to be the AGH, please capture the suspected AGH, take a photograph and send the picture in an email to bee@gov.ab.ca

Vespa mandarinia