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My mother found a hornet at home (in northern France) that is probably building a nest. Is that an asian hornet? If yes, how can I exterminate them?
This is not a hornet, this a wasp. See the yellow dots on the thorax ? They are typical of the Vespula genus. So is the yellow and black stripe pattern on the abdomen. Those wasps are smaller than hornets (1-2 cm for wasps, 3-4 cm for hornets). Picture from Wikipedia:
There are two common Vespula species in France (V. vulgaris and V. germanica), but to identify yours, we would need a better view of the head and abdomen.
On the image below, you can compare it to the two hornet species you can find in France (source). The first one is a bee, the second one is a wasp (Vespula), the third one is the invasive "Asian hornet" (Vespa velutina) and the fourth one is the native "European hornet" (Vespa crabro).
So no extermination needed ;) You can find more information (in French) on how to recognize these species on the Natural History Museum website.
Asian Giant Hornet
Asian giant hornets are the largest known hornet species in the world, typically found in China, Japan and several other Asian countries. The first U.S. sighting of the species occurred in Washington in December 2019. This hornet species prefers to live in low forests and mountains, while avoiding high-altitude climates and plains. Asian giant hornets primarily feed on other insects and are known to attack bee nests and destroy their colonies. Sometimes referred to as “murder hornets” by media outlets, they are reported to kill as many as 50 people a year in Japan, repeatedly stinging targets when their colony is threatened.
My first encounter with hornets
1. General Introduction to Hornets & Yellow-Jackets
Hornets & wasps, so what is the difference?
Hornets and yellow-jackets of the world
Hornets and yellow-jackets of Europe
2. Hornet & Yellow-Jacket Invasions
Accidental introductions of wasps and hornets around the world
What traits helps wasps to invade
The Asian hornet and its European cousins
The Asian hornets&rsquo arrival in France and subsequent spread
The Asian hornets&rsquo arrival in the UK
Was the Asian hornet eradicated from the UK?
The Asian hornets&rsquo arrival in South Korea and subsequent spread
3. Hornet Life Cycle
Hibernation (Oct/Nov to April)
The embryo nest (April/May-June), solitary period
Protection of the embryo nest from ants
Cooperative period (June)
The worker nest (June-August) or polyethnic period
Reproductive phase (September-October)
Colony decline phase (October-November)
4. Hornet Preditors & Pests
Predators of Hornets
Internal parasites of Hornets
5. Hornets as Pests, Food & Control Methods
Hornets attacking Eastern honey bees
Hornets attacking Western honey bees
Hornets as stinging insects
Hornets as pests of fruit crops
Hornets as food for humans
Hornet control methods
Protecting your honey bee colonies
Further reading (books)
Further reading (scientific papers)
Scientists predict potential spread, habitat of invasive Asian giant hornet
The world's largest hornet, the Asian giant hornet has been encountered in the Pacific Northwest. New research at Washington State University predicts where the hornet could find suitable habitat, both in the U.S. and globally, and how quickly it could spread, should it establish a foothold. Credit: WSDA
Researchers at Washington State University have predicted how and where the Asian giant hornet, an invasive newcomer to the Pacific Northwest, popularly dubbed the "murder hornet," could spread and find ideal habitat, both in the United States and globally.
Sharing their discoveries in a newly published article in the Proceedings of the National Academy of Sciences, the team found that if the world's largest hornet gains a foothold in Washington state, it could spread down much of the west coast of the United States.
The Asian giant hornet could also find suitable habitat throughout the eastern seaboard and populous parts of Africa, Australia, Europe, and South America, if humans inadvertently transport it.
The team's predictions underline the importance of Washington state's efforts to stop the large insects before they spread.
"We found many suitable climates in the U.S. and around the globe," said lead author Gengping Zhu, a postdoctoral scholar at WSU's Department of Entomology.
Collaborating with Washington State Department of Agriculture scientist Chris Looney and WSU entomologists David Crowder and Javier Illan, Zhu examined more than 200 records from the hornet's native range in Japan, South Korea, and Taiwan, then used a set of ecological models incorporating climate data to predict likely global habitat across six continents.
"These predictions are scientific sleuthing," Illan said. "We're making an educated guess on how fast and far these insects can move, their rate of success in establishing a nest, and offering different scenarios, from least bad to worst. No one has done this before for this species."
A wide range of suitable habitats
Native to forested parts of Asia, the Asian giant hornet, Vespa mandarinia, is a significant threat to Western honey bees, which have no natural defense. In late summer and fall, hornet colonies attack beehives, destroying entire bee colonies to feed their brood and produce new queens.
Up to two inches long, the insect also deploys a potent sting, which is more dangerous than that of local bees and wasps.
Asian giant hornets are most likely to thrive in places with warm summers, mild winters, and high rainfall. Extreme heat is lethal, so their most suitable habitats are in regions with a maximum temperature of 102 degrees Fahrenheit.
Based on those factors, suitable habitat for the giant hornet exists along much of the U.S. west and east coasts, adjacent parts of Canada, much of Europe, northwestern and southeastern South America, central Africa, eastern Australia, and most parts of New Zealand.
Much of the interior of the U.S. is inhospitable to the hornet due to extremes of heat, cold, and low rainfall. This includes the eastern parts of Washington state and British Columbia, as well as California's Central Valley, all of which have major fruit and nut crops that rely on honey bee pollination.
Danger of accidental spread
Using data from a similar species, Vespa velutina, scientists predicted that without containment, Asian giant hornets could spread into southern Washington and Oregon, and north through British Columbia. Calculating that hornets could fly up to 68 miles per year, their worst-case scenario found that the insects could disperse throughout the western regions of Washington and Oregon in 20 years or less.
However, scientists cautioned that these predictions are an educated guess.
"The information that we want—how fast and far queens can fly, and when they fly—is all unknown," Illan said. "A lot of basic biology is unknown. So, we're using a surrogate."
"We know queens come out of their nest in the fall, mate, and fly—somewhere," Looney said. But nobody knows how far they fly, or if they fly repeatedly. We don't know if they set up nests in the spring near where they hibernated, or if they start flying again. These are some of the things that make predicting natural dispersal a challenge."
Nature alone cannot predict where the hornet may end up. Human activity plays a role in transporting invasive species around the globe.While colonies can only be started by mated queens, and a USDA analysis found that accidental transport by humans is unlikely, Looney said that human-assisted spread could be a concern.
"It's easy for some species to get moved accidentally from one side of the country to the other, even if there's a large swathe of unacceptable habitat in between," he said.
"Preventing the establishment and spread of Asian giant hornet in western North America is critical for protecting bees and beekeepers," Crowder said. "Our study can inform strategies to monitor and eradicate these invaders before they become established."
Is this an asian hornet - Biology
Vespa mandarinia Smith holds the title for being the world&rsquos largest hornet. Commonly referred to as the Asian giant hornet, Vespa mandarinia&rsquos unrivaled size and distinctive markings make it easily distinguishable from other Asian hornet species (Matsuura and Yamane 1990 Figure 1). This wasp&rsquos sting can be life-threatening to humans and it can decimate a number of insect colonies, most notably wild and managed honey bees (Matsuura and Sakagami 1973). Vespa mandarinia is native to Japan and can also be found established outside of its native range in several countries in Asia, in both temperate and tropical climates. Within the United States the first known detection of a Vespa mandarinia hornet was in Washington in fall of 2019 (MGann 2019).
Figure 1. Female Vespa mandarinia Smith, resting. Photograph by Yasunori Koide, Wikimedia commons.
Synonymy (Back to Top)
Vespa japonica Radoszkowski 1857
Vespa latilineata Cameron, 1903
Vespa sonani Matsumura, 1930
Vespa mandarinia bellona Smith, 1871
Vespa mandarinia magifica Smith, 1852
Vespa mandarinia nobilis Sonan, 1929
(Catalogue of Life: 2019 Annual Checklist)
Distribution (Back to Top)
Vespa mandarinia is established in many parts of Asia including Thailand, China, Nepal, Russia, and its native Japan. Currently, this species is not established in western Europe, but sporadic records of its occurrence have been reported in several countries (Pest Tracker 2017, Liu et al. 2016). These hornets prefer to nest in temperate regions, including mountainous areas, but can also be found in some subtropical environments (Matsuura and Sakagami 1973). A colony of Vespa mandarinia was discovered in September 2019 in British Columbia, Canada. This was the first colony found in North America. In the United States, the first appearance of this hornet was reported in the early Fall 2019. The first specimen was collected in December 2019 in Blaine, Washington however, Vespa mandarinia is not considered established in any part of North America at this time (Tripodi and Hardin 2020). Regular monitoring and trapping efforts in Washington will be conducted to note any further occurrences and risk of distribution (McGann 2019).
Description (Back to Top)
Vespa mandarinia individuals are large and robust wasps with several distinctive features that distinguish them from other similar species. The head is wider than other Asian hornet species, specifically above the mandibles and between the eyes (Figure 2). The front of the face above the mandibles (the clypeus) has a deeply scalloped edge, rather than being evenly rounded. The cheeks (genae) are pronounced on both sides of the head, making the head appear noticeably wider in full face view (Figure 2). The genae house the muscles needed to power the large mandibles that play a vital part in the ability of Vespa mandarinia to overpower prey (Matsuura and Sakagami 1973). Adult workers are often slightly shorter than 5.08 cm (2 inches) in length whereas adult queens are close to 5.08 cm (2 inches) (Figure 3). Adults have an overall matte orange-yellow colored head (Figure 1). Banding on the abdomen is yellow and brown, with the last segment uniformly yellow (Matsuura and Yamane 1990 Figure 3).
The head, thorax and abdomen are stout and have varying densities of setae (hairs). In addition to compound eyes, these hornets, like other Hymenoptera, have ocelli (the three light sensing organs between the eyes). The possession of the stinger distinguishes female reproductives (queen) and non-reproductive workers from the stingless males. The stinger is smooth and nearly a centimeter in length (Handwerk 2002). As is characteristic of all Hymenoptera, this hornet has two pairs of wings with the forewing surpassing the body length of 5 cm (2 inches) (Figure 3).
Figure 2. Vespa mandarinia Smith anterior view of head. Photograph by Allan Smith-Pardo , Invasive Hornets, USDA APHIS PPQ.
Figure 3. Vespa mandarinia Smith female adult length. Photograph by Allan Smith-Pardo, Invasive Hornets, USDA APHIS PPQ.
Life Cycle and Biology (Back to Top)
All Vespa mandarinia colonies are established in the spring by mated queens after they have emerged from diapause (period of postponed development). These queens feed on tree sap for energy and first scout for a proper space to start a colony (Makino 2016). Once a queen has selected an adequate location, often in a cavity or hollow area near the roots of trees, she begins constructing the comb from woody materials gathered while foraging. These fibers are then manipulated into cells and surrounding comb with her mandibles. To accommodate the growing colony, these hornets will excavate additional space by removing balls of soil with their mandibles (Matsuura and Yamane 1990).
The queen is solely responsible for the development and safeguarding of the colony. She continues to provide food and protection to her brood until workers begin to emerge (Matsuura and Yamane 1990). After worker emergence, the workers primarily take over these duties while the queen is dedicated to egg laying in the 1000 or more cells of its typically large nest (Matsuura and Sakagami 1973, Matsuura and Yamane 1990).
Larval Vespa mandarinia hornets develop through five larval instars (stages), during which time they are fed either bits of prey tissue or tree sap. After completing larval development, each individual pupates within the covered cell and remains in a cocoon for nearly 18 days (Matsuura and Yamane 1990). The colony size ranges greatly from 4 to 12 comb panels and as many as 3000 distinct cells (Matsuura and Yamane 1990). Each comb lies mostly horizontal, conforming to the available space. The nest cover is often unfinished and consequently the last comb located at the bottom of the nest structure is exposed (Matsuura and Sakagami 1973). These brood cells can vary slightly in depth and width depending on whether they were constructed by the queen or workers. Worker cells have an average diameter of approximately 11 mm while both queen and male cells are 14 mm in diameter. The depth of these cells ranges from approximately 33 mm for workers to 42 mm for queens (Matsuura and Sakagami 1973).
Colonies grow during summer and into fall until a brood of reproductive females (new queens or gynes) and male hornets emerge around the end of October. These male hornets leave the nest and will wait outside nest entrances to mate with new queens emerging from nests. Once the new queens mate, typically with only one male, they begin to search for an ideal overwintering site in the soil where they will remain for nearly seven months before starting their own colonies in the spring (Takahashi et al. 2004). In late fall, around mid-November, founding queens die, and the original colony quickly weakens as workers die off and are not replaced (Matsuura and Yamane 1990).
Predatory Strategies (Back to Top)
Vespa mandarinia workers have a more extensive foraging range than other hornet species (Abe et al. 1991). They tend to attack prey located within two kilometers from the nest but have been noted to travel as far as eight kilometers in search of food (Matsuura and Yamane 1990). These hornets are very assertive when competing for resources during the spring months (Matsuura and Yamane 1990). For example, Vespa mandarinia nestmates will congregate around the sap supply on a tree and prevent other hornet species from feeding (Abe et al. 1991). Insect prey is a vital source of protein for the growing larvae in the nest and Vespa mandarinia most often preys on large beetle species. If accessible, this hornet also preys on honey bees and other wasps among other insects (Matsuura and Yamane 1990).
Vespa mandarinia utilizes a pair of attack strategies to hunt other social insects. For example, the lone hunting mode involves a single hornet worker capturing one honey bee at a time outside the beehive entrance. The hornet kills the bee by detaching the head from the rest of the body at the thorax (Figure 4), then chews it into a gummy paste for transportation back to the nest where it is fed to larvae. Hornets take bees from multiple colonies rather than concentrating on one specific colony. This mode of hunting can inflict minor or major damage to the colonies depending upon the honey bee species, where multiple species exist in its native range. Similarly, another invasive wasp species Vespa velutina attacks honey bee colonies in this way, weakening about 30% of honey bee hives (Monceau et al. 2014). The most famous mode of predation by this hornet, often referred to as a slaughter, it is extremely damaging to the prey colony (Matsuura and Yamane 1990).
Figure 4. Vespa mandarinia Smith processing its honey bee prey capture. Photograph by Scott Camazine.
The slaughter strategy involves groups of 10 to 20 or more Vespa mandarinia nestmates staging a coordinated attack on a single colony by ripping multiple guard bees apart (typically at the head) with their mandibles until no individuals remain to defend the nest entrance (Figure 3). An entire honey bee colony of about 30,000 individuals can be destroyed in several hours with the remains of those workers being left in and around the hive (Matsuura and Yamane 1990, Matsuura and Sakagmai 1973). If there are still survivors come nightfall, the hornets will retire to their nest and reappear the next morning to continue their attack until occupation is complete. Once the majority of the bee workers are destroyed and unable to defend the nest, the hornets retrieve the bee larvae and pupae to feed the nest larvae (Matsuura and Sakagmai 1973). A depiction of this process can be viewed in the National Geographic "Hornets from Hell" video (Handwerk 2002). These types of invasions typically occur in the late summer months when the hornet colonies have produced many workers (Matsuura and Sakagami 1973).
European honey bees, Apis mellifera, are practically defenseless against this predator as they have not evolved strategies to defend their colonies. Honey bee stings are ineffective at deterring the hornet as Vespa mandarinia&rsquos robust cuticle is not susceptible to these stings (Tan et al. 2016). Asian honey bees, Apis cerana, have evolved a stronger group tactical technique because of their historical co-existence with Vespa mandarinia. The bees communicate to each other to begin surrounding (or &ldquoballing&rdquo) the hornet in order to raise their group temperature to approximately 46°C (Figure 5), which is high enough to kill the hornet but not kill themselves (Egelie et al. 2015, Ugajin et al. 2012).
Figure 5. Asian honey bees, Apis cerana, defensively &ldquoballing&rdquo a single Vespa mandarinia Smith. Photograph by Masato Ono, Tamagawa University.
Medical Significance (Back to Top)
Any interaction with stinging insects can pose risks to those who are allergic to the venom however, Vespa mandarinia has been associated with severe responses in those who are not considered anaphylactic or allergic (Yanagawa et al. 2007). This hornet&rsquos defensive nature intensifies the risk for serious medical complications in humans. In Japan it is estimated that approximately 40 people die from the stings each year (Yanagawa et al. 2007). These deaths have been contributed to kidney failure, anaphylactic shock, heart attacks, and multiple organ failure often from multiple stings (Yanagawa et al. 2007). During a four-month period in 2013, Vespa mandarinia caused 42 deaths and 1,675 injuries in China. In the cases of injuries that lead to hospitalization, it often took about 30 days for recuperation (Liu et al. 2016). Further, these hornets can cause scars from stinging that can endure for some years (Matsuura and Yamane 1990).
Economic Importance (Back to Top)
Management of Vespa mandarinia is quite difficult because of the stinging risk and lack of accessibility to the nests. In the past, Japanese inhabitants have used physical elimination as well as chemicals to kill and reduce Vespa mandarinia colonies, though they are difficult to locate and kill below ground. Insecticides such as ready-to-use aerosols and concentrates are utilized by the U.S. Department of Defense in efforts to control other species of oriental hornets (Army Public Health Center). Some beekeepers have taken to using mechanical devices including specially designed screening to assist with defending and protecting the bees at the hive entrances (Matsuura and Yamane 1990). While there are homemade devices used by some beekeepers in Europe, there are also commercial products such as false bottom boards that trap hornets attempting to invade managed honey bee hives.
Sustained monitoring efforts should be employed for early detection of Vespa mandarinia in a region and evaluation of its potential establishment. This species has the potential to negatively impact human health and honey bee colonies, particularly managed Apis mellifera (Matsuura and Sakagami 1973). As honey bees play a significant role in the pollination of crops, establishment of Vespa mandarinia in the United States could have a severe impact on agriculture and the economy as well as on human health. Continuous monitoring and subsequent elimination of any discovered colonies is paramount to prevent Vespa mandarinia establishment.
Selected References (Back to Top)
- Abe T, Tanaka Y, Miyazaki H, Kawasaki YY. 1991. Comparative study of the composition of hornet larval salvia, its effect on behavior and role of trophallaxis. Comparative Biochemistry and Physiology 99: 79-84. https://doi.org/10.1016/0742-8413(91)90079-9
- Army Public Health Center. Oriental Hornets. Fact Sheet 18-074-0616. (27 October 2019)
- Catalogue of Life: 2019 Annual Checklist. 2019. Species Details: Vespa mandarinia Smith, 1852. (26 June 2019)
- Egelie AA, Mortensen AN, Gillett-Kaufman JL, Ellis JD. 2015. Apis cerana Fabricius (Insecta: Hymenoptera: Apidae). University of Florida, IFAS, Entomology and Nematology Department. Featured Creatures, EENY 616. (29 September 2019)
- Handwerk B. 2002. "Hornets from Hell" Offer Real-Life Fright. National Geographic News. (11 January 2020)
- Liu Z, Li X, Guo B, Li Y, Zhao M, Shen H, Zhai Y, Wang X, Liu T. 2016. Acute interstitial nephritis, toxic hepatitis and toxic myocarditis following multiple Asian giant hornet stings in Shaanxi Province, China. Environmental and Preventative Medicine 21: 231-236. https://doi.org/10.1007/s12199-016-0516-4
- Makino S. 2016. Post-hibernation ovary development in queens of the Japanese giant hornet Vespa mandarinia (Hymenoptera: Vespidae). Entomological Science 19: 440-443. https://doi.org/10.1111/ens.12205
- Matsuura M, Sakagami SF. 1973. A bionomic sketch of the giant hornet Vespa mandarinia, a serious pest for Japanese apiculture. Journal Faculty of Science 19: 125-162.
- Matsuura M, Yamane S. 1990. Biology of the Vespine Wasps. Berlin. Springer-Verlag. pp. 1-323.
- McGann C. 2019. Pest Alert: Asian giant hornet. Washington State Department of Agriculture. (1 April 2020)
- Monceau K, Bonnard O, Thiéry D. 2014. Vespa velutina: A new invasive predator of honeybees in Europe. Journal of Pest Science 87: 1-16.
- Ono M, Igarashi T, Ohno E, Sasaki M. 1995. Unusual thermal defense by a honeybee against mass attack by hornets. Nature 377: 334-336. https://doi.org/10.1038/377334a0
- Pest Tracker: Exotic Pest Reporting. 2017. Survey Status of Asian giant hornet - Vespamandarinia. (25 June 2019)
- Smith-Pardo A. 2018. Invasive Hornets, USDA APHIS PPQ, Bugwood.org. (27 October 2019)
- Takahashi J, Akimoto S, Martin SJ, Tamukae M, Hasegawa E. 2004. Mating structure and male production in the giant hornet Vespa mandarinia (Hymenoptera: Vespidae). Applied Entomology Zoology 39: 343-349. https://doi.org/10.1303/aez.2004.343
- Tan K, Dong S, Li X, Liu X, Wang C, Li J, Nieh JL. 2016. Honey bee inhibitory signaling is tuned to threat severity and can act as colony alarm signal. PLoS Biology 14: e1002496. https://doi.org/10.1371/journal.pbio.1002423
- Tripodi A, Hardin T. 2020. New Pest Response Guidelines. Vespa mandarinia Asian Giant Hornet. United States Department of Agriculture. (13 April 2020)
- Ugajin A, Kiya T, Kunieda T, Ono M, Yoshida T, Kuno T. 2012. Detection of neural activity in the brains of Japanese honeybee workers during the formation of a &ldquoHot Defensive Bee Ball&rdquo. PLoS One 7: e32902. https://doi.org/10.1371/journal.pone.0032902
- Yanagawa Y, Morita K, Sugiura T, Okada Y. 2007. Cutaneous hemorrhage or necrosis finding after Vespa mandarinia (wasp) stings may predict the occurrence of multiple organ injury: A case report and review of literature. Clinical Toxicology 45: 803-807. https://doi.org/10.1080/15563650701664871
Authors: Caitlin Gill, Cameron Jack, and Andrea Lucky, University of Florida
Photographs: Yasunori Koide, Wikimedia commons Allan Smith-Pardo , Invasive Hornets, USDA APHIS PPQ Scott Camazine Masato Ono, Tamagawa University.
Web Design: Don Wasik, Jane Medley
Publication Number: EENY-754
Publication Date: May 2020
The study was carried out on workers of Vespa velutina nigrithorax (also known as yellow-legged or Asian hornets), found foraging in SW France and in Jersey. At the time of the study (July and September 2017) V. velutina nests were building towards maturity with hundreds to thousands of workers searching for insect prey to feed developing brood in their colonies. The purpose of the technique developed was to find nests before reproductives (gynes and males) were produced (typically between September and December 10 ).
Methods were developed and tested within the grounds of INRA Bordeaux-Aquitaine, in the southern suburbs of Bordeaux (Villenave d’Ornon, Gironde, southwestern France). Method development (cold anaesthesia, tag attachment and recovery post-handling) took place from 17 to 24 July 2017 tests of tagged hornet flight performance took place from 25 to 27 July and 13 to 21 September 2017. Tagged hornets were tracked in Villenave d’Ornon on 27 July and between 13 and 21 September 2017 under warm, dry conditions (average daily temperatures = min 10.4 °C, max 22.2 °C average daily rainfall = 1.9 mm average wind speed = 3.5 m s −1 ). We also tested the technique on V. velutina in Jersey (Crown Dependency of the UK, located 14 miles from the north west coast of France), which has a much lower density of hornets as they have newly established here 8 . Testing and tracking was carried out between 25 and 28 September 2017 at the States of Jersey Department of Environment (Howard Davis Farm, La Route de la Trinité, Trinity, Jersey JE3 5JP) and near to points of capture in and around the Durrell Wildlife Park (Trinity) and New Zealand Avenue, St Saviour. These parishes are predominately rural with some semi-urban development (average daily temperature = min 13.8 °C, max 18.8 °C average daily rainfall = 2.8 mm average wind speed = 4.2 m s −1 ).
The Pip19 (with Ag190 battery) and PicoPip (with Ag337 battery) radio tags (both from Biotrack Ltd, UK) were deemed the most suitable as they were among the lightest, smallest VHF tags available. They are sold in various configurations differing in location of the battery relative to the tag electronic circuit board and orientation of their aerial. Initial attempts utilised tags in Biotrack’s Option A configuration (with batteries on top of circuit boards generating a shorter, fatter tag: 8 mm long × 5 mm wide × 4 mm tall) but subsequently tags in Biotrack’s Option C configuration (with battery fixed at the end the circuit board generating a longer, slimmer tag: 13 mm long × 5 mm wide × 2 mm tall) were preferred as these fitted better under the abdomen of a V. velutina worker. All tags had a 100 mm aerial in the same plane as the length of the tag (hence trailing behind it), although these could be shortened but with a loss in range in doing so. Pip19/Ag190 tags weighed 0.222 g (SD ± 0.016 g range = 0.195–0.245 g includes a small 7 mg metal loop glued to the tag for attachment as described below) and were activated by cutting a connecting wire on the side of the tag. Once activated, Pip19 tags with a pulse length of 15 ms and pulse frequency of 28–32 ppm (pulses per minute) had a manufacturer’s expected lifespan of 4 days. PicoPip/Ag337 tags weighed 0.280 g (SD ± 0.012 g range = 0.256–0.312 g including the small 7 mg metal attachment loop) and were activated by removal of a magnet linked to an integral reed switch. Once activated, PicoPip tags with a pulse length of 19–20 ms and a pulse rate of 39–46 ppm had a manufacturer’s expected lifespan of 12 days. Reed switches come with a slight weight penalty but were preferred during testing as such tags could be readily activated and deactivated when reusing tags on different hornets (a factor less relevant to tracking as hornets were infrequently re-caught following field release). Reed switches were not utilised with Pip19 tags as the weight penalty was considered proportionally more substantial. Testing of representative Pip19 and PicoPip tags in a flat open landscape (Predannack airfield, Ruan Major, UK) indicated expected detection ranges of approx. 250 m (max. 375 m) and approx. 500 m (max. 817 m), respectively.
Each tag operated at a specific frequency within the band designated for wildlife telemetry within that country (in France = 150.xxx MHz in UK including Jersey = 173.xxx MHz). Tags of different frequencies were used to ensure activated tags could be distinguished in the field. The frequencies were preprogrammed into a Sika radio tracking receiver (138–174 MHz band width Biotrack Ltd, UK), fine-tuned to each individual tag, and signal detection confirmed with a suitable Yagi antenna (Biotrack Ltd, UK) before release of a tagged individual.
To test the capabilities of hornets to carry tags of differing weights, we utilised Pip19 and PicoPip tags (either active or with expired batteries) and further expanded the weight range tested by utilising home-made mimics of such tags, made from short lengths of electric mains core wrapped in insulating tape and with a thin 100 mm aerial, to an equivalent size, shape and relevant weight.
All tags had a very small metal wire loop (resistant to bite action by the hornet) glued on to front edge of the tag, allowing the tag and aerial to trail behind from this attachment point (see below for attachment to hornet). As live tags were encased by the manufacturer in either varnish or Plastidip, the tags were made not only water resistant but avoided the attached wire loop short-circuiting the tag electronics. Each tag was marked with either a unique identifier provided by the manufacturer or by the addition of unique mark (e.g. numbered and coloured honeybee queen marking disc glued to dummy tags). Before use, each tag was weighed, with their metal wire attachment loop in place, on an electronic laboratory balance.
Attachment of the radio tag
Vespa velutina hornets were caught in an insect net while hawking outside beehives, foraging around a willow tree, or foraging at artificial bait stations (prawn-baited in Bordeaux Trappit ® wasp attractant baited in Jersey). Once caught, individual hornets were transferred via 50 ml Falcon centrifuge tubes (with ventilation hole/slit in cap) to the laboratory where they were weighed on an electronic laboratory balance. To avoid testing or tracking V. velutina gynes, queens or males, female individuals weighing <0.500 g were selected 10 . Selected individuals were cold anaesthetised by embedding the Falcon tube, with hornet, to its full length in crushed ice for a minimum of 10 min or until the hornet no longer showed discernible movement (max. 12 min). Once anaesthetised, a hornet would be secured to a bespoke restraining plate (Supplementary Fig. 1). The abdomen of an anaesthetised hornet would be carefully manoeuvred under the wire tie on the plate, ensuring wings and legs were free of entrapment, before the wire ends were pulled tight, lowering the hoop, between abdomen and thorax, across the hornet’s petiole. The 20 mm distance between drilled holes and the stiffness of the wire ensured that the wire would restrain the hornet to the plate without damaging it, even when the wire was pulled very tight. The wire ends were secured by bending them over opposite edges of the restraining plate. Thin cotton sowing thread was next fed though the head of the T-shaped cut in the restraining plate, over the hornet’s petiole, and back down through the head of the T-shaped cut in the restraining plate (avoiding legs, wings and wire tie). The thread was drawn sufficiently tight and thread ends tied in a knot to produce a thread loop around the petiole that was loose enough to allow free movement but close enough to prevent a hornet from reaching and biting the thread loop. The remaining ends of cotton thread were then passed though the small metal wire loop previously attached to the radio tags and tied in a further tight knot. Knots were further secured by a small dap of superglue, and surplus lengths of thread removed close to the final knot. An anaesthetised V. velutina worker would partially recover within the short time (<5 min) needed to attach a tag but would remain secure on the restraining plate. To ensure subsequent identification of individuals, a unique coloured and numbered honeybee queen marking disc was glued (Loctite Super Glue Power Flex Gel Control) on to the dorsal surface of the thorax of each hornet.
The above tag arrangement and attachment permitted a radio tag to be secured to a central ventral point of the hornet, with the attachment point beyond reach of the hornet’s mandibles, but nevertheless allowing sufficient movement in the tag enabling the hornet to manoeuvre past obstacles when on a surface. In flight, the tag and aerial would trail below and slightly behind the hornet with little direct impact on flight (earlier attempts at fitting tags to the dorsal side of the thorax proved top-heavy and led to hornets flipping over and falling to ground unpublished data).
Once marked and tagged, a hornet was released into a ventilated recovery cage (0.6 m x 0.6 m x 0.7 m) by loosening the wire tie and guiding the hornet and tag along the T-shaped slit until free from the restraining plate and secured in the cage. Hornets were given 10 min to recover from anaesthesia and handling within the cage in which food (honey, fruit syrup and water) was provided ad libitum. This recovery period also permitted released hornets to begin to adapt flight behaviour to take account of the weight and size of attached tags. Ad hoc observations during this period also permitted checks to confirm tags were attached in a manner permitting the hornets to walk and fly within the confines of the cage.
Testing whether tagged V. velutina can fly
Flight performance of 47 tagged hornets was assessed in an outdoor flight cage (3 m x 3 m x 2 m insect-proof and pollination netted cage from Diatex SAS, France ref. PE16/13.28), or on field release near point of initial capture (37 hornets in both, 7 in the flight cage only, and 3 on field release only see Supplementary Table 1). For ease of release, the recovery cage was placed inside the outdoor flight cage on a raised platform. On completion of the recovery period, a selected hornet was placed on the roof of the recovery cage and released to assess its flight performance over the subsequent 10 min. A released hornet would either walk or fly to the edge of the roof and launch into the air towards the perimeter of the flight cage. From the approx. 1.3 m vantage of the recovery cage roof, a hornet would descend to the ground, achieve near horizontal flight, demonstrate slight ascending flights, or variants between these. As well as an opportunity to assess flight performance, this period in the flight cage was also a further opportunity for hornets to adapt to the presence of radio tags. Hornets that landed on the ground were either guided towards the flight cage netting to allow them to climb to a height, or lifted back on to the recovery cage roof. Flight performance was assessed based on repeated flights or flight attempts within the 10 min period, and rated on a scale of 1−5 (1 = sharp descending flights only or no flights 2 = mainly descending flights 3 = both horizontal and descending flights 4 = mainly horizontal flights 5 = ascending and strong horizontal flights). On a conservative basis, hornets rated 4 or 5 were subsequently categorised as good flyers and hornets rated 1 to 3 were categorised as poor flyers within the flight cage.
On completion of the flight performance assessment in the flight cage, hornets were transferred to an open field location. Using blunt forceps, a hornet would be placed on a gloved hand held approx. 1.6 m above the ground. The hornet was allowed to fly off when ready or, if remained stationary for over 5 min, was gently encouraged to depart by slight movement of the forceps near the hornet. A hornet was permitted three attempts to fly beyond reach. If all three attempts were descending towards the ground, the hornet was classified as a poor flyer and recovered. If the hornet flew beyond reach (e.g. into a tree at >12 m from the release site, or beyond a distance where it was visually discernible), it was categorised a good flyer. Hornets that were fitted with active radio tags and subsequently tracked were included in these flight assessments.
Tracking tagged V. velutina to their nests
Ten tagged V. velutina workers prepared for tracking were transferred to a field location, close to where they had been caught: seven hornets in France and three hornets in Jersey. Two hornets were fitted with Pip19 tags and eight hornets with PicoPip tags. The functioning of the active tags was verified by tuning the Sika radio tracking receiver to the preprogrammed channel and checking for a detectable signal via Sika receiver with Yagi antenna prior to release.
A V. velutina worker selected for release was placed on an elevated surface (either the roof of a parked car or on a gloved hand both approx. 1.6 m above the ground). As previously during flight performance assessments, each hornet was given no more than three attempts to fly from an elevated location. All ten V. velutina workers flew either to a nearby tree or flew beyond a distance where they were visually discernible. In all cases, the release time, GPS coordinates (latitude and longitude) of the release site and vanishing direction (i.e. compass bearing) from the release point were recorded. The visually determined vanishing direction was also confirmed as the direction providing the strongest signal from the tag attached to the released hornet.
The tracking team, made up of a Sika receiver operator and data recorder, would quickly relocate along the vanishing direction, checking for the direction of strongest signal reception. The tracking team was restricted to using public roads or paths, municipal recreational areas, or land where prior permission to enter had been sought. Consequently, the tracking team could not follow the hornets’ flight paths directly but had to triangulate from accessible locations. Variation in the detected signal’s strength or direction from a location would indicate whether a tagged hornet was likely stationary or in flight. Although principally a direction indicator, adjustment of the gain/sensitivity of the Sika receiver would indicate whether a hornet was close, on occasions confirmed by visual sightings of a tagged hornet. The time, signal direction and GPS coordinates of various waypoints along a tracking route were recorded as well as any observational notes such as foraging activity around nectar-rich food sources (e.g. flowering ivy covered trees). When the detected signal was deduced to converge on a single location from various waypoints over a period of 5–10 min, the location in question was visually checked through binoculars looking for evidence of a nest (usually within the leaf canopy of a tree), concentrated hornet traffic (suggesting a concealed nest) or the tagged hornet, or else to determine whether it was a likely foraging site (evidenced by abundant nectar-rich flowers such as ivy and associated hornet activity). Such searching continued until either observed or daylight faded. When a nest was found, its location was recorded and the local hosts (INRA in France and Department of Environment in Jersey) informed to enable them to activate the locally appropriate management plan and limit the impact of V. velutina.
Each captured hornet was weighed and all behavioural information recorded after tagging, through to the location of nests. For a range of tag weights and hornet weights, the tag:hornet weight ratio was calculated to determine the threshold relating to good flight performance (Fig. 2). Distances between release point and nest location were calculated from the latitude and longitude of the two points (Fig. 3). All data are included in the Supplementary Tables.
Flight performance was divided into two classes: poor and good flyers, for tests both within the cage and outside. A Fisher’s exact test on the two-by-two contingency table (Table 1) was used to test for association between performances of individuals inside and outside the cage, to explore whether flight within the cage was a good indicator of flight outside the cage.
The authors declare that all data supporting the findings of this study are available within the article and Supplementary Tables 1–3.
Asian Giant Hornets – Their Venom Dissolves Skin
The title about says it all. Asian giant hornets (Vespa mandarinia) are pretty terrifying – they’re the largest hornets in the world, reaching around 5 cm (2 inches) in length, or about the size of a person’s thumb. And they can kill a person if they get stung enough. They live in parts of Asia and are most common in rural Japan, where they’re known as the “giant sparrow bee,” but right now it’s in China that they’re causing the most problems. Since July in China, more than 1,600 people have been injured, and 42 killed, by being stung by the enormous hornets (and some smaller types). It’s thought that a recent heat wave is part of the issue – colder weather should hopefully push the giants into hibernation soon.
An asian giant hornet (Vespa mandarinia). (Image credit: KENPEI)
Other than their sheer massive size, what’s most fascinating and horrifying about the giant hornets is their sting. Not only is their stinger quite large (about 6 mm, or 0.25 inches in length), but the venom they inject with it contains several chemicals that work in different ways to damage the recipient. Some of these chemicals basically dissolve tissue. For example, one is a phospholipase, which means that it breaks down and destroys cell membranes. And without a cell membrane, a cell cannot do much – it falls apart and dissolves. (Another chemical in the venom, specifically called mastoparan, works by stimulating phospholipase activity, so it pretty much does the same thing but indirectly.) So when someone is stung by an Asian giant hornet, the excruciatingly painful sting leaves behind a small hole of dissolved skin.
And to make matters worse, a single hornet can sting multiple times (unlike bees and some other wasps, which have barbed stingers that prevent them from pulling it out). And it actually gets even worse than that – the hornets can release chemicals that attract other hornets, so a person can be targeted by an entire hive, which can chase that person at speeds up to 25 mph. If a person is stung five times, depending on their reaction (some people are allergic) they can die due to kidney failure. In China right now they’re recommending people to seek medical attention if they’re stung more than 10 times. This may seem like a lot of stings, but a single nest is often large enough to have over 1,000 hornets, and just in the last week more than some 4,000 nests like this have been destroyed in China. Clearly there’s reason to be on the lookout for things flying around outside, and for camouflaged nests that one might stumble upon.
As a side note, while these hornets don’t have any natural predators, they are actually frequently eaten as a regular food source by people who live near them. So while people are working hard to destroy the hornets and their nests, at least the hornets themselves may be put to some good nutritional use.
Here's how experts plan to eradicate the "murder hornets," a newfound invasive scourge
By Nicole Karlis
Published May 4, 2020 7:03PM (EDT)
Japanese Giant Hornet – Vespa mandarinia (Getty Images/Alastair Macewen)
A pile of dead bees, some with heads torn from their bodies. This grisly scene is the result of a "murder hornet" making its way through a bee hive, according to a New York Times report that went viral over the weekend.
Amid a pandemic, it seems unfair to have nature inflict another curveball on the Earth — in this case, an invasive killer hornet species called the Asian Giant Hornet, which can be deadly to humans. But it in 2020, anything is possible. Though it is unclear if the giant hornet, whose scientific name is Vespa mandarinia, is responsible for aforementioned scene of apian slaughter, scientists greatly suspect it: two of the killer hornets were found a few miles north from the site in Blaine, Washington, in December 2019. These marked the first sightings of murder hornet in the United States, who had come a long way from their home in Southeast Asia and Japan. There have been two additional unconfirmed reports of murder hornets near Custer, Washington.
Washington State Department of Agriculture scientists are now taking the lead to find, trap and eradicate the hornets, which are the largest in the world and have the ability to sting multiple times, even through a beekeeper's suit. Murder hornets can deliver seven times the amount of venom as a honey bee, which is equivalent to that of a venomous snake.
Should humans be worried? To some degree, yes, but there's no need to panic yet, experts say. (In other words, the coronavirus remains a far bigger existential threat.) And while there have only been a few sightings, scientists fear murder hornets could multiply in population to the point that they threaten economy or ecology.
"We've only had a couple locations in Canada and one location in Washington State where we've found the hornets late last year in 2019," Todd Murray, Director of Washington State University's (WSU) Agricultural and Natural Resources Extension Program Unit, told Salon over email. "Our goal is to stop any further spread if they have, by chance, established nests in Canada or Washington."
In Japan, where they are common, these hornets kill an estimated 50 people a year. As reported by Wired , if the hornets don't see you as a threat, they'll leave you alone — like most animals. A sting can also be quite painful, as reported by one blog that quoted a sting victim who described the experience as "like a hot nail through my leg."
Murray said education is a key part of stopping the spread.
"Currently WSU Extension and WSDA (Washington State Department of Agriculture) are educating Washingtonians about the problem, how to identify Asian Giant Hornets and how to report any potential sightings this summer," Murray said. "It is important for people [to report]. if they 'see something, say something.' We have developed multiple ways for people to report potential sightings WSDA is also deploying an extensive trapping program to help identify any potential nesting sites."
If any nests are found, the WSDA will be the agency to kill and destroy the nests.
Murray emphasized that they believe they will be able to eradicate the invasive hornets before they get a foothold in the United States.
"Our entomologists have a very good chance at eradicating any populations in Washington State because someone reported this early," he said. "I am confident that we have caught this problem early and that our entomologists will be able to eradicate the local populations of hornets if they have established."
It's also important to note that humans face an indirect risk, as the hornets are bee killers. Since farmers rely on bees to pollinate huge numbers of crops, and given that bee populations are already under threat, there may be serious biological and economic consequences if bees have to face yet another predator.
"The major concern about this insect establishing in Washington state and US or even North America, is their impact on honey bee production and pollination services," Murray said. "Asian Giant Hornets can significantly impact honey production where they occur naturally or where similar species have been introduced in Europe. Also our concern is that this insect could also harm our native pollinators like bumble bees and other nesting bees."
Intentional or not, when an invasive species enters a new ecosystem it creates lasting effects and changes to its environment.
This isn't the first time an invasive insect with a menacing name has spooked Americans. Africanized bees, colloquially known as killer bees, were first introduced in the United States in 1990.
Murray said he is hopeful.
"I am optimistic that we caught this one early and we won't have to learn how to live with this species," he said. "I definitely don't want to learn to live with Asian Giant Hornets."
Asian hornets were inadvertently brought to France in 2004, most likely in a shipment of goods imported from east Asia. Since arriving in France, the species has spread rapidly. It is now present across France and is moving into adjoining countries.
The Asian hornet is a non-native species in the UK, as it hails from east Asia and could not arrive in the UK naturally.
The concern around the Asian hornet is that it is a significant predator of bees. In France, it has consumed large numbers of bees, including the well-known European honey bee and many lesser-known solitary and colonial bee species. Nature conservation organisations, including the RSPB, are concerned about the impacts of Asian hornets on bees, as these pollinating species are an essential component of well-functioning ecosystems.
The Asian hornet is undoubtedly an invasive non-native species in France, and the evidence indicates it would be invasive in the UK too. It has been recorded in the UK on at least three occasions (as of January 2018). However, the relevant authorities swiftly eradicated these individuals.
Learn more about the Asian hornet
Learn more about how to identify an Asian hornet, and how to report a sighting, by visiting our blog.
More research needed on giant Asian hornet (aka the 'Murder hornet') says local expert
As one of a handful of experts in North America with firsthand experience studying Asian giant hornets, also known as the 'murder hornet,' retired University of Guelph professor Gard Otis is uniquely positioned to understand the species&rsquo recent arrival in the continent.
Sightings of the Asian giant hornet in Washington State and British Columbia last fall have raised concerns about the potential threat to honey bee populations, crops and humans from a species nicknamed &ldquomurder hornets.&rdquo
Otis is an expert in honeybee biology and insect ecology. He worked on various beekeeping projects in Vietnam over a period of seven years, including studying a &ldquosister species&rdquo hornet in 2013.
&ldquoI don't think I could tell the difference between (the species) by looking at them,&rdquo he said. &ldquoI feel like I know this animal even though I haven't seen it (here).&rdquo
The Asian giant hornet is the world&rsquos largest hornet. It typically lives in countries like Japan and China. Queens can grow up to two inches long, and are known for their massive wings, armoured bodies and toxic stinger. They are also known to decimate entire colonies of honey bees by decapitating them with spiked mandibles and then flying away with the thoraxes to feed their young.
Asian giant hornets don&rsquot often attack humans, but in swarms, they have been known to kill a few dozen people a year in parts of Asia with their toxic venom and excruciating sting.
Otis says that while the introduction of this species to North America is concerning, it is not altogether surprising. He cites another Asian species - the yellow-legged hornet - that was introduced into Europe over 10 years ago.
&ldquoDespite all the efforts to contain it and to try to prevent it from increasing, it just keeps expanding its range,&rdquo he said. &ldquoSo, we already knew that this was a possibility.&rdquo
Little is known about how the species actually made it into North America, but Otis says one likely explanation is that a single mated queen &ldquohibernated&rdquo in a lumber shipment and then became active in its new environment in the spring.
&ldquoWhen we have an invasive insect that's been detected, we have a short period of time to try to contain it before it gets so abundant that the game is over,&rdquo he said. &ldquoSo, since we only discovered them last fall, there's a hint that we might be able to stop them.&rdquo
But Otis is doubtful that enough can be done to stop the hornets entirely from expanding their presence. Rather, he says the focus should be on continued research about the species and its basic biology to inform appropriate action.
&ldquoIt is not yet an established population. We don't know anything about how common they are, how genetically diverse they are. We don't know how this will play out,&rdquo he said. &ldquoState and provincial governments are going to try to get samples and there will be studies coming out. But in the early stages, we're going to be in destroy mode.&rdquo
Many experts, Otis included, resent the species&rsquo ominous nickname. Dennis Schmidt is the president of the Wellington County Beekeepers&rsquo Association, which provides outreach and education to beekeeping hobbyists in the area. He feels that the recent buzz in the media is somewhat sensationalized.
&ldquoIt's interesting to see how much publicity [the hornet] is getting,&rdquo he said. &ldquoIt does look a little bit like a villain from a superhero movie. It's very frightening in appearance and the size is really intimidating. But I don't think that we're going to see any practical concern on a local level.&rdquo
While the Asian giant hornet generally thrives in temperate climates, it remains to be seen whether it can also survive Canadian winters. But Schmidt says Ontario beekeepers are more concerned with other imported pests such as the hive beetle from the southern United States and killer bee genetics from California.
&ldquoWith the number of bees that are shipped around the world, pests are now able to spread very quickly,&rdquo he said. &ldquoSo far, we've been pretty lucky in Ontario &hellip but I think that there is an impending fear that the current state of the industry is going to be shaken up.&rdquo
Still, if the Asian giant hornet does reach Ontario, Schmidt has faith in the province&rsquos ability to deal with such a threat.
&ldquoThere is a very well-established protocol that's overseen by the Ontario Ministry of Food, Agriculture and Rural Affairs (OMAFRA). We have a very strong and capable beekeeping association in Ontario (OBA) and they're very active in lobbying the government to control potential risks,&rdquo he said.
In the meantime, Otis has found himself being called upon as a valuable local source of expertise on this particular species. He says this underscores the importance of basic scientific research.
&ldquoBasic biology - that&rsquos really my roots. A lot of the time, you can't predict when the research is going to have value . just doing it sometimes is useful.&rdquo