Regulated invasive species of Union concern under the European Regulation on the prevention and management of the introduction and spread of invasive alien species [1143/2014].
Invasive species - risk of High Impact
Introduction pathways - 1
Introduction pathways subclass - 1
Introduction pathways - 2
Introduction pathways subclass - 2
Natural dispersal across borders of invasive aliens
NAPRA Ireland risk assessed
Workers can be up to 25mm long, while queens may reach in excess of 30mm, which is considerably larger than any of our wasp species. The thorax is a velvety dark brown or black and the abdomen is dark with the exception of the 4th segment, which is yellow. Legs have yellow tips, from which it takes its other common name the 'yellow-legged hornet'. The head is black with an orange face (Botham et al., 2016). Males can be differentiated from workers by their lack of a stinger (Monceau et al., 2014).
This day flying hornet (Hymettus, 2010) is a predator of honeybees (Apis mellifera), wasps, other pollinators, such as hoverflies (European Commission, 2017) and spiders (Rome et al., 2011), which it uses primarily to feed the larvae (Monceau et al., 2014). These prey are important for pollination of crops as well as wild flora (Marris, 2011). As such it may have serious impacts on biodiversity and pollination services through predation. However, the literature is lacking on the impacts of this invasive species. Its main food source is the honeybee (Villemant et al., 2011). The hornet hovers at the entrance to the hive and attacks bees returning from foraging from below, forcing them to the ground and subduing them with their sting. Later on in the season, due to increased pressure on the workers to supply protein for the production of gynes (potential queens), they may attempt to enter the hive to predate the brood (Rome et al., 2011; Botham et al., 2016). They will also take honey reserves (Marris, 2011). Colonies can reach 10,000 individuals during autumn and losses of 14,000 honeybees per hive per month have been recorded in France (European Commission, 2017). The hornets are active from April to November with a peak in August and September. The adults mainly consume carbohydrates in the form of sugar so they also feed on fruit, nectar (NNSS, undated) and tree sap (Monceau et al., 2014). They may have an impact on commercial fruit growers. Their success and rapid spread in Europe may be due to the lack of interspecific competition out of their native range (Villemant et al., 2011). Although not aggressive outside their home range, stings do occur and are painful but not usually dangerous in isolation.
In March the inseminated queen comes out of hibernation and flies to look for a suitable place for the nest. She builds a nest of pulped wood fibre mixed with saliva usually high in a tree. Once the primary nest has been built she begins laying eggs. The first workers (sterile females) emerge in June. Throughout the summer the size of the colony and the nest are increased (Monceau et al., 2014). Colonies may number 10,000 individuals per season (European Commission, 2017). In the autumn the queen starts to lay the eggs that will produce gynes (potential queens) and males. Autumn is when mating and dispersal occurs (Monceau et al., 2014). All hornets with the exception of the gynes die by the beginning of winter (Hymettus, 2010). Both mated and unmated gynes over-winter singly or in groups by hibernating in small, well insulated crevices but it is unclear what happens to the unmated gynes (Monceau et al., 2014).
Pathway and vector description
Can be introduced as a contaminant on wood products, live trees e.g. mature olive trees, other commodities, in vehicles e.g. containers on ships/trucks or on fruit or flowers (Marris, 2011). The species was initially introduced to France in 2004 (NNSS, 2017) possibly with goods imported from China. From there, with the queens being highly mobile and adaptable, it has spread rapidly to Germany, Italy, Portugal and Spain (European Commission, 2017).
A hornet was discovered in Devon in the UK in September 2017. The nest has since been found and destroyed (www.nonnativespecies.org). It is conceivable that inseminated queens could make their way to Ireland should colonies establish in the UK.
Mechanism of impact
Competition, Predation, Poisoning/Toxicity
Eradication is generally considered impossible once widespread (Monceau et al., 2014).
Impact on honeybees can be reduced by decreasing the size of the entrance to the hive until it is just a small slit, too small for the hornets to enter. Predation of flying bees may still occur but the brood will remain unharmed (Hymettus, 2010).
Management should be targeted at nest destruction. This method may be useful to control local predation (Monceau et al., 2014). The species is diurnal so destruction should be carried out at sunrise or sunset wearing adequate protection (Rome et al., 2011). Health and safety considerations should be taken into account for personnel as nests are often 10m up trees. Insecticides (pyrethrins, Marris 2011) are used to fumigate the nest. Once all the hornets have been killed the nest should be removed to prevent poisoning of wildlife e.g. birds. Shortcomings of this method are that emerging gynes may leave the nest during fumigation and that nests are very well hidden and may not be detected until they are a very large size (Monceau et al., 2014) or until autumn leaf fall (Botham et al., 2016).
Builds nests in tall trees (avoids conifer monocultures) or on manmade structures. Nests are sometimes built close to the ground. Most likely to be seen close to bee hives (NNSS, undated).
Temperate Asia, Tropical Asia
Vespula germanica, Vespula vulgaris, Vespula rufus, Vespula austriaca, Dolichovespula sylvestris, Dolichovespula norvegica. All these species are considerably smaller than Vespa velutina nigrithorax.
In the EU has been introduced in France, Germany, Italy, Portugal, Spain and is spreading rapidly (European Commission, 2017).
Native to Bangladesh, Bhutan, China, India, Indonesia, Korea Republic, Laos, Malaysia, Myanmar, Thailand, Vietnam (Marris, 2011).
Records submitted to Data Centre in 2021
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How can you help
Report any sightings immediately to the National Biodiversity Data Centre.
Delivering Alien Invasive Species In Europe (DAISIE) project list this as one of the 100 Worst Invaders in Europe.
Botham, M., Hubble, D. & Roy, H. (2016) Asian hornet, Vespa velutina Factsheet. Non-native Species Secretariat (NNSS). http://www.nonnativespecies.org/factsheet/downloadFactsheet.cfm?speciesId=3826 Site accessed 25 October 2017.
European Commission. (2017). Invasive Alien Species of Union Concern. European Union, Luxembourg.
GB Non-native Species Secretariat (NNSS) (undated) Alert poster for Vespa velutina, Asian hornet. www.nonnativespecies.org Site accessed 21 October 2017.
GB Non-native Species Secretariat (NNSS) (2017) Species description – Asian hornet. www.nonnativespecies.org Site accessed 21 October 2017.
Hymettus (2010) Information sheet 12: Asian hornet (Vespa velutina). Text by Stuart Roberts, Quentin Rome & Claire Villemant. www.nonnativespecies.org Site accessed 21 October 2017.
Marris et al. (2011). GB Non-native Organism Risk Assessment for Vespa velutina nigrithorax. www.nonnativespecies.org Site accessed 21 October 2017.
Monceau, K., Bonnard, O., Thiéry, D. (2014) Vespa velutina: a new invasive predator of honeybees in Europe. Journal of Pest Science 87:1–16 http://www.kmonceau.fr/wp-content/uploads/2011/08/Monceau-et-al.-Review-Vespa-velutina1.pdf Site accessed 25 October 2017.
Rome, Q., Perrard, A., Muller, F., Villemant, C. (2011) Monitoring and control modalities of a honeybee predator, the yellow-legged hornet Vespa velutina nigrithorax (Hymenoptera: Vespidae). Aliens: The Invasive Species Bulletin Newsletter of the IUCN/SSC Invasive Species Specialist Group, 31: 7-15 https://www.researchgate.net/profile/Ahmet_Uludag/publication/292606052_Challenges_needs_and_future_steps_for_managing_invasive_alien_species_in_the_Western_Balkan_Region/links/587bc9ed08ae4445c0642e63/Challenges-needs-and-future-steps-for-managing-invasive-alien-species-in-the-Western-Balkan-Region.pdf#page=9 Site accessed 25 October 2017.
Villemant, C., Barbet-Massin, M., Perrard, A., Muller, F., Gargominy, O., Jiguet, F. , Rome, Q. (2011). Using niche models to predict the global invasion risk by the alien bee-hawking yellow-legged hornet Vespa velutina nigrithorax across Europe and other continents. Biological Conservation 144: 2142-2150 https://adrienperrard.files.wordpress.com/2013/02/villemant_etal_2011-biolinv.pdf Site accessed 26 October 2017.