Vespa? Scoot on Over...

It’s looking more and more likely that the people of New Zealand are destined for co-habitation with yellow-legged hornets as more and more discoveries are announced around Auckland. What would we be in for should they become established – from their behaviours to how they might impact the country’s economy – and what control methods do we have at our disposal?

By Dave Black

It’s not just the yellow legs which give away the yellow-legged hornet’s identity.

Since June 2025, according to MPI, Biosecurity New Zealand have confirmed a number of detections of the yellow-legged hornet (Vespa velutina) across Auckland. First described in 1836 by the French entomologist Amédée Louis Michel Lepeletier in his Histoire Naturelle des Insectes—Hyménoptères[i], in July two male yellow-legged hornets were spotted in the Auckland suburbs of Grafton and Albany, apparently resting on the outside of buildings. No nests were located.

Like our local Vespa wasp species, mating occurs in autumn and queens overwinter, so further sightings of locally-resident hornets would not be expected until Spring was under way. Almost right on cue, on October 17 a queen hornet was confirmed nesting in Glenfield, the nest being removed and destroyed the same day. Two more sightings followed. It seems there are still more to be discovered (with 27 queens, two workers and 17 nests reported at time of writing, November 28); my money is on an over-wintered nest that has produced fertile queens.

Originally from South-east Asia the natural range of V. velutina extends from Kashmir to Taiwan, and south to Java and Timor. In parts of its native range these hornets are cultivated and managed for food and medicinal products in similar ways to bumble bees and other hymenoptera[ii]. The sub-species found here is a descendent of a continental group of hornets nearly all of which live in China, from which it has been accidentally introduced into South Korea, Europe and Japan[iii] [iv]. V. velutina is considered a threat to these ecosystems because of its predation on insect pollinators, but brings a more diverse set of ecological and economic implications. There is no reason why this hornet could not colonise any of the regions in New Zealand already home to our other invasive wasp species.

Poking a Hornet’s Nest

Hornets are predatory social wasps, one of the many varieties of Vespa (Vespidae), several of which interact with honey bees. The only species specifically adapted to predate honey bees are the eight sub-species of the under-ground-nesting giant hornet V. mandarinia, but many hornets, and V. velutina is one, eat honey bees as a part of their diet. Because the Auckland finds are being described as ‘yellow-legged’, open-nesting Asian hornets, we can infer that we are dealing with Vespa velutina nigrithorax to give its full name[v], and among other things that tells us where in the world it originated.

Separating hornet types is a job for specialists, especially when the specimens can often be damaged or incomplete. Size is not a good guide, to either type or caste, as it’s highly dependent on an individual’s natal conditions, but most hornets are a little larger than a queen bee. Colour is not an infallible guide to species[vi], but dark, ‘smoky’ wings are quite characteristic of all hornets, and the general body shape definitely more Ferrari than Fiat.

The naming and identification of the various sub-species is still evolving and actively debated, but around 12-17 subtly different types of V. velutina are described in the scientific literature[vii], the features of which get all blended into a savage ‘super-wasp’ in the public imagination. Popular videos of ‘Asian’ hornets usually feature the particularly aggressive and ferocious V. mandarina, but many hornet species have made the ‘most not wanted’ list for invasive animals.

What’s for Lunch?

In a recent French survey of food pellets supplied by 12,200 hornets to 16 nests (2,151 pellets) velutina was characterised as an opportunistic generalist predator, preying mainly on honeybees (38.1 %), flies (29.9 %), and social wasps (19.7 %), but at least 159 prey species were found in total[viii]. As we might expect, there was some variation that depended on what prey was available, so the ‘catch’ depended on, for example, whether the habitat was agricultural or forested, time of day, and of season. This dietary adaptability is actually one of the keys to it being such a successful species and what permits it to invade new habitats. While they will eat your bees, they will also eat the wasps that were going to eat your bees later, or anything else that comes to hand.

V. velutina are known to use scent to detect distant feeding opportunities, and a different French group have studied this in more detail[ix]. Rather than noticing bees, these hornets are attracted by the scents from bees’ nests. In multiple choice tests performed as a controlled laboratory assay, the research found that the hornets are strongly attracted to the odour of some hive products, especially pollen and honey. The smell of honey bees themselves was only marginally attractive.

When testing specific compounds, the honey bee’s aggregation pheromone, ‘geraniol’ produced by the nasonov gland, proved highly attractive. Also, the synthetic honeybee queen mandibular pheromone, Beeboost, was somewhat interesting and prolonged visit duration. Surprisingly, alarm pheromones did not elicit much response. What hornets are looking for, it seems, is an area of high prey density, rather than the prey itself.

On the Move

V. velutina construct more than one nest in a season, possibly as a strategy to mitigate the limitation of having a single individual found the colony. The first ‘primary’ nest, or queen colony, is made by the solitary queen in the spring, and it’s the quality of this nest, in terms of brood raised, that sets up the overall seasonal reproductive success of the colony – or not, many fail[x]. Once brood production expands beyond the capacity of this initial nest workers search for better sites in the vicinity. The queen will subsequently abandon the nest she built and the workers will construct a new and larger secondary nest at her chosen site.

Once the queen has left it takes about a month for all the brood in the primary nest to reach adulthood and migrate to the secondary nest. This nest will grow full of workers during the summer and when mature can produce potentially several hundred queens and drones in the autumn[xi] [xii]. Over-wintering queens are not always successfully mated.

It’s the Economy Stupid...

The impacts of hornets outside their native range are significant,[xiii]besides the ecological harm, a permanent presence of hornets here will rock the food security boat and is likely to add an unwanted complication to export certification for our own producers. In economic terms there is the damage to bee colonies and honey production, and the concomitant damage to the yield of insect-pollinated crops, regardless of pollinator. The cost of mitigating these impacts by monitoring and controlling hornets – and destroying nests – for an indefinite period are also not insignificant. The effect on the balance of invertebrates in native ecosystems is mostly indeterminable, as is the cost of the ‘by-catch’ by control attempts. The actual annual cost of nest destruction alone has been estimated at around €10 million (NZD17m) each in France, Italy and the UK[xiv].

Hornets also benefit from a close association with human spaces in suburban and urban environments; primary nests especially are mainly reported in man-made structures as diverse as garages, light fixtures, and bird boxes, and adults are frequently found hunting near suburban apiaries. Humans have a habit of putting a lot of ‘stuff’ in a small area, which makes hunting for food more efficient. This natural proximity to hornets can pose a significant hazard for public safety.

The statistics we have to describe human injuries caused by these hornets are poor; insect-related fatalities are rare but not negligible[xv]. In China a number of deaths occur each year due to organ failure and the toxic effect of mass-envenomation after a multiple sting event. Like other hymenoptera, V. velutina are also responsible for fatal anaphylactic deaths and a Spanish university in Santiago de Compostela has reported an exponential increase in the proportion of allergic events involving V. velutina. They write; “...considering the number of patients receiving venom immunotherapy, while 60.3% of 126 patients were being treated with Apis mellifera venom in 2015, 68.2% of 245 were being treated with Vespula spp venom in June 2019, the majority of them after suffering anaphylaxis due to VVN [Vespa velutina nigrithorax]”[xvi].

Another report shows annual mortality rates due to hornet, wasp, and bee stings have shown an increasing trend in Spain over a 1999-2018 study period[xvii]. This appears to be at least partially due to increases in regions where introduced hornets are found, and have been more profound in the ten or so years since the hornets arrived. The necessity to plan and fund changes to public health provision to respond to an elevated risk like this also takes time and money.

A yellow legged hornet, Vespa velutina, in the wild.

Action Stations...

A solution to all this will prove elusive. Finding and catching the invaders is difficult. Protecting beehives is possible to an extent, but protecting our other pollinating insects is not. People find it hard to avoid a flying insect which hides its nests. However, there are some useful lessons to be taken from years of overseas experience[xviii]. The first lesson is, it only takes one. Eileen Dillane and her colleagues at University College in Cork, Ireland have presented genetic evidence that shows the entire European population of V. velutina (many millions of insects) has descended from the entry of a single queen twenty years ago[xix] [xx].

Early detection of invasive species is essential[xxi], and most countries immediately established ‘citizen-science’ teams, involved beekeeper associations to gather observations, and tried using monitoring traps. Beekeepers are more adept, but there are too few of them. Border surveillance and local monitoring has had limited success, but prompt action in at least two jurisdictions has eliminated the incursions. However, the probability of seeing a hornet is low, even for beekeepers, who might spend quite a bit of time in their home apiary but visit out-apiaries sparingly.

Catch and Release

The purpose of using traps is to catch (alive) and trace velutina individuals. None of the current traps are suitable as a control method, and their efficacy as a monitoring tool is quite limited unless it’s combined with gene sequencing[xxii] [xxiii]. As with Covid19, genetic tracing of all the finds has proved invaluable in other incursions, and can indicate how many nests we are looking for.

Current trapping methods are not particularly selective, and not very attractive (unless they are beehives!). Although a sex pheromone trap could be made, it would attract only males[xxiv] which isn’t particularly helpful. So far no trap, or trap-bait, has proved to be particularly effective, and all collect a considerable number of dead non-target species, including but not only honey bees[xxv]. So far, commercial products and baits don’t seem to be any more effective or selective than DIY versions. In Brec’t, (Brittany, northwestern France) the beekeepers’ favourite recipe is said to consist of beer, grenadine syrup, and a splosh of white wine.

So far no trap, or trap-bait, has proved to be particularly effective, and all collect a considerable number of dead non-target species, including but not only honey bees. But electric “harps” such as setup in front of these six beehives have been used overseas.

The key to repelling the intruders is the eradication of nests, preferably before they release inseminated queens, which is only possible if they can be found[xxvi]. Observations are used in a variety of ways to try and triangulate the location of nests using the ‘homing’ flight direction of captured individuals, but it needs systematic preparation, good data handling, training, a lot of sightings, and can take days if not weeks. Multiple nests confuse and defy triangulation. Odd things have been statistically associated with nests, the presence of camellia plants(!), and water (for papier-mache construction).

Thermal imaging has not proved to be very useful for locating nests. Harmonic radar (already used to track bees) which involves fitting trapped hornets with a passive responder didn’t work well in forested or urban environments and has signal strength limitations. Recently, radio telemetry using an active radio tag has proved a success, but isn’t widely available[xxvii]. It still requires hornets that have been netted and cold-anaesthetised to be fitted with the transponder so they can be followed.

Seek and Destroy

Other controls have been used in apiaries. Fipronil protein-baits, or sugary baits laced with alcohol[xxviii], have been used for decades to try and reduce wasp predation, but it needs an element of knowledge and restraint as it can be dangerous to other species. The ingredient is often regulated or banned because of its risk in the environment and effects on people that are, at best, unpleasant.  Potentially highly effective, in practice its success can rest on seasonal factors. There is already a worrying amount of fipronil in the environment that results from pet flea treatments. If you are an ‘approved’ user in New Zealand the commercial product ‘Vespex’ is an example of this type of approach, where the bait is collected and carried back to be fed to larvae, but it’s likely that it would need to be reformulated to attract V. velutina or that different pre-feeding regimes might be helpful.

There are also physical barriers used in apiaries, (for sale or home-made) that exploit the size of hornets. In parts of Europe hive ‘muzzles’ have been tried and these seem partly successful[xxix]. Essentially, a landing and take-off zone at the front of the hive is guarded by a wire cover that bees can fly through but hornets cannot. A rather more effective and substantial solution is an ‘electric harp’, in which wires separated by just less than a hornet wing span (18-20mm) carry an electric current produced by a solar panel[xxx]. Bees fly through the harp easily but hornets contact both wires, shorting the current which kills them. A pre-commercial version, the ‘Velzapper’, has proved to be highly selective, more than 90% of its ‘catch’ being velutina, but it remains to be shown that enough hornets can be captured by the tool to lower predation to a sustainable level[xxxi].

Destined for Co-Habitation

All of these ‘solutions’ are really just tinkering at the edge of the problem, as they aren’t useful for hundreds or even thousands of hives deployed as mobile pollination units, circumstances quite different to the small, static, suburban European apiaries they have been trialled in. If velutina becomes established in New Zealand, and to me both the initial lukewarm response and the prevailing disunity in the apiculture community suggest it is quite probable, we’ll need to put our thinking caps on. The problem is not going to go away even if this particular incursion does, humans and hornets are destined to inhabit the same planet for quite a while.

Dave Black is a commercial-beekeeper-turned-hobbyist, now retired. He is a regular science writer providing commentary on “what the books don't tell you”, via his Substack Beyond Bee Books, to which you can subscribe here.

References

[i]Ashman, K., Keller, O., Jack, C., 2020. Yellow-Legged Hornet (suggested common name), Vespa velutina (Lepeletier 1836) (Insecta: Hymenoptera: Vespidae). EDIS 2020, 5. https://doi.org/10.32473/edis-in1282-2020

[ii]Van Itterbeeck, J., Feng, Y., Zhao, M., Wang, C., Tan, K., Saga, T., Nonaka, K., Jung, C., 2021. Rearing techniques for hornets with emphasis on Vespa velutina (Hymenoptera: Vespidae): A review. Journal of Asia-Pacific Entomology 24, 103–117. https://doi.org/10.1016/j.aspen.2021.03.009

[iii]Lioy, S., Bergamino, C., Porporato, M., 2022. The invasive hornet Vespa velutina : distribution, impacts and management options. CABI Reviews cabireviews202217030. https://doi.org/10.1079/cabireviews202217030

[iv]Arca, M., Mougel, F., Guillemaud, T., Dupas, S., Rome, Q., Perrard, A., Muller, F., Fossoud, A., Capdevielle-Dulac, C., Torres-Leguizamon, M., Chen, X.X., Tan, J.L., Jung, C., Villemant, C., Arnold, G., Silvain, J.-F., 2015. Reconstructing the invasion and the demographic history of the yellow-legged hornet, Vespa velutina, in Europe. Biol Invasions 17, 2357–2371. https://doi.org/10.1007/s10530-015-0880-9

[v]Vidal, C., 2022. The Asian wasp Vespa velutina nigrithorax : Entomological and allergological characteristics. Clin Experimental Allergy 52, 489–498. https://doi.org/10.1111/cea.14063

[vi]Perrard, A., Arca, M., Rome, Q., Muller, F., Tan, J., Bista, S., Nugroho, H., Baudoin, R., Baylac, M., Silvain, J.-F., Carpenter, J.M., Villemant, C., 2014. Geographic Variation of Melanisation Patterns in a Hornet Species: Genetic Differences, Climatic Pressures or Aposematic Constraints? PLoS ONE 9, e94162. https://doi.org/10.1371/journal.pone.0094162

[vii]Smith-Pardo, A.H., Carpenter, J.M., Kimsey, L., 2020. The Diversity of Hornets in the Genus Vespa (Hymenoptera: Vespidae; Vespinae), Their Importance and Interceptions in the United States. Insect Systematics and Diversity 4, 2. https://doi.org/10.1093/isd/ixaa006

[viii]Rome, Q., Perrard, A., Muller, F., Fontaine, C., Quilès, A., Zuccon, D., Villemant, C., 2021. Not just honeybees: predatory habits of Vespa velutina (Hymenoptera: Vespidae) in France. Annales de la Société entomologique de France (N.S.) 57, 1–11. https://doi.org/10.1080/00379271.2020.1867005

[ix]Couto, A., Monceau, K., Bonnard, O., Thiéry, D., Sandoz, J.-C., 2014. Olfactory Attraction of the Hornet Vespa velutina to Honeybee Colony Odors and Pheromones. PLoS ONE 9, e115943. https://doi.org/10.1371/journal.pone.0115943

[x]Archer, M.E., 2010. The queen colony phase of vespine wasps (Hymenoptera, Vespidae). Insect. Soc. 57, 133–145. https://doi.org/10.1007/s00040-009-0063-8

[xi]Asperges, M., Vanstraelen, Z., n.d. Voracious larvae of the Asian hornet Vespa velutina nigrithorax (Hymenoptera: Vespidae). https://doi.org/doi.org/10.6084/m9.figshare.26385460

[xii]Rome, Q., Muller, F.J., Touret‐Alby, A., Darrouzet, E., Perrard, A., Villemant, C., 2015. Caste differentiation and seasonal changes in Vespa velutina (Hym.: Vespidae) colonies in its introduced range. J Applied Entomology 139, 771–782. https://doi.org/10.1111/jen.12210

[xiii]Diéguez-Antón, A., Escuredo, O., Seijo, M.C., Rodríguez-Flores, M.S., 2025. Long-term Vespa velutina nigrithorax pressure: Honey bee risk survival to alien invasion. Apidologie 56, 34. https://doi.org/10.1007/s13592-025-01158-z

[xiv]Barbet-Massin, M., Salles, J.-M., Courchamp, F., 2020. The economic cost of control of the invasive yellow-legged Asian hornet. NB 55, 11–25. https://doi.org/10.3897/neobiota.55.38550

[xv]Feás, X., Vidal, C., Remesar, S., 2021. What We Know About Sting-Related Deaths? Human Fatalities Caused by Hornet, Wasp and Bee Stings in Europe (1994-2016)

[xvi]Vidal, C., Armisén, M., Monsalve, R., González-Vidal, T., Lojo, S., López-Freire, S., Méndez, P., Rodríguez, V., Romero, L., Galán, A., González-Quintela, A., 2021. Anaphylaxis to Vespa velutina nigrithorax: Pattern of Sensitization for an Emerging Problem in Western Countries. J Investig Allergol Clin Immunol 31, 228–235. https://doi.org/10.18176/jiaci.0474

[xvii]Feás, X., 2021. Human Fatalities Caused by Hornet, Wasp and Bee Stings in Spain: Epidemiology at State and Sub-State Level from 1999 to 2018. Biology 10, 73. https://doi.org/10.3390/biology10020073

[xviii] Leza, M., Herrera, C., Picó, G., Morro, T., Colomar, V., 2021. Six years of controlling the invasive species Vespa velutina in a Mediterranean island: The promising results of an eradication plan. Pest Management Science 77, 2375–2384. https://doi.org/10.1002/ps.6264

[xix] Claire Villemant Jean Haxaire et Jean-Claude Streito, Premier bilan de l'invasion de Vespa velutina Lepeletier en France (Hymenoptera, Vespidae), Bulletin de la Société entomologique de France, 111 (4), 2006: 535-538.

“Data transmitted by the SRPV1 of Aquitaine suggests that the introduction of Vespa velutina into France predates 2004: a bonsai grower in Sainte-Livrade-sur-Lot saw brown hornets flying as early as the summer of 2004. He recognized the species, having observed it during a trip to China shortly before. In the autumn of 2004, after the leaves had fallen, he discovered two spherical nests in nearby trees and destroyed them with a shotgun. In 2005, upon seeing them flying again, he captured one and, in 2006, sent a specimen to one of us (J.-C. S.), who confirmed its identification. According to the bonsai grower, this Asian hornet may have been introduced in the boxes of Chinese pottery that he has been regularly importing from Yunnan for several years. Since the transport of goods by boat only lasted a month, the survival of fertilized females inside the boxes could have been achieved without problem if these were shipped during the winter period.”

[xx]Dillane, E., Hayden, R., O’Hanlon, A., Butler, F., Harrison, S., 2022. The first recorded occurrence of the Asian hornet (Vespa velutina) in Ireland, genetic evidence for a continued single invasion across Europe. JHR 93, 131–138. https://doi.org/10.3897/jhr.93.91209

[xxi]Lioy, S., Manino, A., Porporato, M., Laurino, D., Romano, A., Capello, M., Bertolino, S., 2019. Establishing surveillance areas for tackling the invasion of Vespa velutina in outbreaks and over the border of its expanding range. NB 46, 51–69. https://doi.org/10.3897/neobiota.46.33099

[xxii] Budge, G.E., Hodgetts, J., Jones, E.P., Ostojá-Starzewski, J.C., Hall, J., Tomkies, V., Semmence, N., Brown, M., Wakefield, M., Stainton, K., 2017. The invasion, provenance and diversity of Vespa velutina Lepeletier (Hymenoptera: Vespidae) in Great Britain. PLoS ONE 12, e0185172. https://doi.org/10.1371/journal.pone.0185172

[xxiii] Jones, E.P., Conyers, C., Tomkies, V., Semmence, N., Fouracre, D., Wakefield, M., Stainton, K., 2020. Managing incursions of Vespa velutina nigrithorax in the UK: an emerging threat to apiculture. Sci Rep 10, 19553. https://doi.org/10.1038/s41598-020-76690-2

[xxiv] Wen, P., Cheng, Y.-N., Dong, S.-H., Wang, Z.-W., Tan, K., Nieh, J.C., 2017. The sex pheromone of a globally invasive honey bee predator, the Asian eusocial hornet, Vespa velutina. Sci Rep 7, 12956. https://doi.org/10.1038/s41598-017-13509-7

[xxv] Rojas-Nossa, S.V., Novoa, N., Serrano, A., Calviño-Cancela, M., 2018. Performance of baited traps used as control tools for the invasive hornet Vespa velutina and their impact on non-target insects. Apidologie 49, 872–885. https://doi.org/10.1007/s13592-018-0612-0

[xxvi] Wang, C., Huang, J., Wan, X., Guo, Z., 2024. A Review of Five Existing Hornet-Tracking Methods. Insects 15, 601. https://doi.org/10.3390/insects15080601

[xxvii] Kennedy, P.J., Ford, S.M., Poidatz, J., Thiéry, D., Osborne, J.L., 2018. Searching for nests of the invasive Asian hornet (Vespa velutina) using radio-telemetry. Commun Biol 1, 88. https://doi.org/10.1038/s42003-018-0092-9

[xxviii] Barandika, J.F., De La Hera, O., Fañanás, R., Rivas, A., Arroyo, E., Alonso, R.M., Alonso, M.L., Galartza, E., Cevidanes, A., García-Pérez, A.L., 2023. Efficacy of Protein Baits with Fipronil to Control Vespa velutina nigrithorax (Lepeletier, 1836) in Apiaries. Animals 13, 2075. https://doi.org/10.3390/ani13132075

[xxix] Requier, F., Rome, Q., Villemant, C., Henry, M., 2020. A biodiversity-friendly method to mitigate the invasive Asian hornet’s impact on European honey bees. J Pest Sci 93, 1–9. https://doi.org/10.1007/s10340-019-01159-9

[xxx] Rojas‐Nossa, S.V., Dasilva‐Martins, D., Mato, S., Bartolomé, C., Maside, X., Garrido, J., 2022. Effectiveness of electric harps in reducing Vespa velutina predation pressure and consequences for honey bee colony development. Pest Management Science 78, 5142–5149. https://doi.org/10.1002/ps.7132

[xxxi] Pérez-Granados, C., Bas, J.M., Artola, J., Sampol, K., Bassols, E., Vicens, N., Bota, G., Roura-Pascual, N., 2024. Testing the selectiveness of electric harps: a mitigation method for reducing Asian hornet impact at beehives. Journal of Apicultural Research 63, 360–366. https://doi.org/10.1080/00218839.2023.2277988