Asian giant hornet


The Asian giant hornet, also known as the northern giant hornet, and the Japanese giant hornet, is the world's largest hornet. It is native to temperate and tropical East Asia, South Asia, mainland Southeast Asia, and parts of the Russian Far East. It was also briefly found in the Pacific Northwest of North America from late 2019 but was eradicated by December 2024.
Asian giant hornets prefer to live in low mountains and forests, while almost completely avoiding plains and high-altitude climates. V.mandarinia creates nests by digging, co-opting pre-existing tunnels dug by rodents, or occupying spaces near rotten pine roots. It feeds primarily on larger insects, colonies of other eusocial insects, tree sap, and honey from honeybee colonies. The hornet has a body length of, a wingspan around, and a stinger long, which injects a large amount of potent venom.

Taxonomy and phylogeny

V.mandarinia is a species in the genus Vespa, which comprises all true hornets. Along with seven other species, V.mandarinia is a part of the V.tropica species group, defined by the single notch located on the apical margin of the seventh gastral sternum of the male. The most closely related species within the species group is V.soror. The triangular shape of the apical margin of the clypeus of the female is diagnostic, the vertex of both species is enlarged, and the shape of the apex of the aedeagus is distinct and similar.
Division of the genus into subgenera has been attempted in the past, but has been abandoned, due to the anatomical similarity among species and because behavioral similarity is not associated with phylogeny. The species has existed since the Miocene epoch, as indicated by fossils found in the Shanwang Formation.
As of 2012, three subspecies were recognized: V.m.mandarinia, V.m.magnifica, and V.m.nobilis. The former subspecies referred to as V.m.japonica has not been considered valid since 1997. The most recent revision in 2020 eliminated all of the subspecies rankings entirely, with "japonica", "magnifica", and "nobilis" now relegated to informal non-taxonomic names for different color forms.

Common names

After its discovery in North America, the scientific literature and official government sources referred to this species by its established common name, Asian giant hornet, whilst the mainstream media took to using the nickname "murder hornet". In July 2022, the Entomological Society of America stated that they will adopt the common name northern giant hornet for the species to avoid potentially discriminatory language, citing xenophobia and racism related to the COVID-19 pandemic.

Description

Regardless of sex, the hornet's head is a light shade of orange and its antennae are brown with a yellow-orange base. Its eyes and ocelli are dark brown to black. V.mandarinia is distinguished from other hornets by its pronounced clypeus and large genae. Its orange mandible contains a black tooth that it uses for digging. The thorax is dark brown, with two grey wings varying in span from.
Its forelegs are brighter than the mid- and hindlegs. The base of the forelegs is darker than the rest. The abdomen alternates between bands of dark brown or black, and a yellow-orange hue. The sixth segment is yellow. Its stinger is typically long and delivers a potent venom that in cases of multiple hornets stinging simultaneously, or by rare allergic reaction, can kill a human.

Queens and workers

The queens are considerably larger than workers. Queens can exceed, while workers are between. The reproductive anatomy is consistent between the two, but workers do not reproduce.

Drones

are similar to females, and can attain in length, but lack stingers. This is a consistent feature among the Hymenoptera.

Larvae

e spin a silk cocoon when they complete development and are ready to pupate. Larval silk proteins have a wide variety of potential applications due to their wide variety of potential morphologies, including the native fiber form, but also sponge, film, and gel.

Genome

The mitochondrial genome is provided by Chen et al., 2015. This information has also been important to confirm the place of the wider Vespidae family in the Vespoidea superfamily, and confirms that Vespoidea is monophyletic.

Misidentifications

Within two days of the initial 2020 news report on V.mandarinia, insect identification centers in the Eastern United States began getting identification requests, and were swamped for the next several months, though not one of the thousands of submitted photos or samples was of V.mandarinia, but were instead primarily wasps such as the European hornet, the eastern cicada killer, or the southern yellowjacket.
Submissions suspected by laypeople to be V.mandarinia also included other wasps of various sizes, bees, sawflies, horntails, wasp-mimicking flies, beetles, Jerusalem crickets, cicadas, and even a plastic children's toy that was wasp-like in appearance, all of which were routinely estimated to be 130–185% of their actual size.
Reports of this species from other parts of the world appear to be erroneous identifications of other introduced hornet species, such as V.orientalis in several locations around the world, and V.velutina in Europe.

Distribution

Ecological distribution

V.mandarinia is primarily a forest dweller. When it does live in urban landscapes, it is highly associated with green space. It is the most dependent upon green space of the Vespa species. Extremely urbanized areas provide a refuge for V.analis, whereas V.mandarinia – its predator – is entirely absent.

Geographic distribution

Asia

The Asian giant hornet can be found in:
The first confirmed sightings of the Asian giant hornet in North America were confirmed in 2019 and were mainly concentrated in the Vancouver area, with nests also discovered in neighboring Whatcom County, Washington, in the United States. The last confirmed sightings were in 2021.
  • In August 2019, three hornets were found in Nanaimo on Vancouver Island, and a large nest was found and destroyed shortly thereafter.
  • At the end of September, a worker was reported in Blaine, Washington.
  • Another worker was found in Blaine in October.
  • In December 2019, another worker was found in Blaine.
  • Two specimens were collected in May 2020, one from Langley, British Columbia, about north of Blaine, and one from Custer, Washington, southeast of Blaine.
  • One queen sighting in June 2020 was from Bellingham, Washington, south of Custer.
  • An unmated queen was trapped in July 2020, near Birch Bay, Washington, west of Custer.
  • A male hornet was captured in Custer, Washington, in July 2020.
  • A hornet of unknown caste was reported in August 2020, in Birch Bay, and another was trapped in the same area the following day.
  • Three hornets were seen southeast of Blaine on 21 and 25 September 2020, and three more were found in the same area on 29 and 30 September, prompting officials to report that attempts were underway to pinpoint and destroy a nest believed to be in the area.
  • In October 2020, the Washington State Department of Agriculture announced that a nest was found above ground in a cavity of a tree in Blaine, with dozens of hornets entering and leaving. The nest was eradicated the next day, including the immediate discovery and removal of about 100 hornets. At first, the owner of the land required the nest to be returned, and he advertised it for sale. A local beekeeper bought it from him and gave it back to the state entomology team. Further analysis determined that the nest had contained about 500 live specimens, including about 200 queens. Some of these specimens were sent to the Smithsonian Institution to become a part of the NMNH Biorepository permanent cryogenic collection. It was announced that several undiscovered live nests were also believed to exist within Washington State, because the captures of individual hornets in Birch, Blaine, and Custer were all relatively far from the discovered nest. However, officials expressed cautious optimism, adding that eradicating the hornets before they became established in the area might still be possible. A Canadian official said that although individual specimens had been found in Canada and some nests were suspected to exist there, the hornets' presence seemed to be only in areas near the US-Canadian border, while the center of the invasion appeared to be in Washington.
  • In November 2020, one individual was found in Abbotsford, BC. As a result the BC government asked Abbotsford beekeepers and residents to report any sightings.
  • In November 2020, a queen was found in Aldergrove, BC.
  • In August 2021, a nest was discovered in Whatcom County, Washington near Blaine, only from the nest WSDA eradicated in 2020. This nest was destroyed two weeks later on 25 August, before it could produce new queens.
  • In September 2021, two more nests were found near Blaine, in the vicinity of the nest found in August, and a "potential sighting" was reported from near Everson, some east of Blaine.
A mitochondrial DNA analysis was performed to determine the maternal population ancestral to the British Columbia and Washington introduced populations. The high dissimilarity between these two was similar to the mutual distances between each of the Chinese, Japanese, and Korean native populations suggesting the specimens collected in 2019 were from two different maternal populations, Japanese in BC and South Korean in Washington. This suggests that two separate introductions of the Asian giant hornet occurred in North America within about of one another within a few months.
In April 2020, authorities in Washington asked members of the public to be alert and report any sightings of these hornets, which are expected to become active in April if they are in the area. If they become established, the hornets "could decimate bee populations in the United States and establish such a deep presence that all hope for eradication could be lost." A "full-scale hunt" for the species by the WSDA was then underway. Two assessment models of their potential to spread from their present location on the US–Canadian border suggested that they could spread northward into coastal British Columbia and Southeast Alaska, and southward as far as southern Oregon. The USDA's Agricultural Research Service is engaged in lure/attractant development and molecular genetics research, both as part of its normal research mission, but also to further the near-term eradication goal in Washington.
In 2020, the United States Congress considered specific legislation to eradicate V.mandarinia including a proposal by the interior secretary, the Fish and Wildlife director, and the other relevant agencies, which has been introduced as an amendment to the appropriations omnibus. British Columbia Agriculture is prepared for a "long fight" lasting years, if necessary. One advantage humans will have is the lack of diversity of such an invasive population – leaving the hornets less prepared for novel environments and challenges.
In June 2021, a dead, desiccated male was found near Marysville, Snohomish County, Washington, and reported to WSDA. Its different, more reddish color form immediately suggested yet another parental population from the Japanese and Korean ones already known. The USDA Animal and Plant Health Inspection Service performed a genetic analysis several days later, and together with WSDA, confirmed it was of a third, unrelated population. The discovery of a male in June is "perplexing" given that the earliest male emergence in 2020 was July, which was already earlier than normal for the home range. This and its desiccated state indicate it did not emerge in 2021 at all, but is instead a dead specimen that had already emerged in a previous year.
The WSDA announced in December 2022 that "no confirmed sightings" of the hornet were reported in the state for that year, and in December 2023 stated no sightings occurred that year, and in December of 2024, WSDA declared that the hornets had been eradicated from North America.