Asian hornet (Vespa velutina)

Also known as: yellow-legged hornet
Synonyms: Vespa auraria, Vespa fruhstorferi, Vespa immaculata
KingdomAnimalia
PhylumArthropoda
ClassInsecta
OrderHymenoptera
FamilyVespidae
GenusVespa (1)
SizeAdult queen length: up to 3 cm (2) (3)
Adult worker length: up to 2.5 cm (3)
Top facts

The Asian hornet has yet to be classified on the IUCN Red List.

Considered to be one of the most aggressive hornets in its natural range (4), the Asian hornet (Vespa velutina) is a large, wasp-like insect measuring up to three centimetres in length (3) (5). This species has a dark brown to black velvety body (2) (3) (4) (5), with each segment of the body being edged with a thin band of yellow, except for the fourth segment which has a wide yellow to yellow-orange band (2) (3) (4). The Asian hornet has yellow-tipped legs (3) (5), and the front section of its black head between its antennae is orange (4).

There are around a dozen known subspecies of the Asian hornet (2).

The Asian hornet is native to Asia (3) (4), where it occurs from Afghanistan (6) across India and Pakistan (1) to eastern China and Indonesia (2) (4) (6).

However, Vespa velutina nigrithorax, a subspecies of the Asian hornet, has been accidentally introduced to south-western France, being first detected in the country in 2005 (4). It has since expanded its range rather rapidly (2) (3) (4) (5) and has also spread into Spain (4) (6). Today, the Asian hornet is well established in certain parts of France, predominantly the southwest, being found in an area extending almost 300 kilometres north to south, and about 200 kilometres west to east (2). This insect is also considered to be an invasive species in South Korea, where it became established in 2003 (7).

The Asian hornet tends to make its nest high up in the branches of trees, but it is also known to nest in well-ventilated, man-made structures such as sheds and barns (2) (3), as well as occasionally in under-floor cavities (2). Within its introduced range in France, the Asian hornet is known to favour oaks, poplars and acacia trees (8).

The Asian hornet is considered to be a generalist predator (4), with a diet which depends on what is locally available and on the stage of the hornet colony’s development (2). Although the Asian hornet is known to be a major predator of honey bees (2) (3) (6) (8) (9), it also feeds on other insects such as wasps, crickets, butterflies and flies (2) (3) (4) (8), as well as on spiders and even vertebrate flesh (4) (8). Interestingly, the Asian hornet has also been documented eating ripe fruit (2) (3) and flowers (3).

Insect prey is usually caught on the wing (5), with the Asian hornet hovering over the entrance to a hive and catching foraging honey bees returning with nectar or pollen. The hornet forces its prey to drop to the ground before paralysing it and carrying it away (2). In this way, the Asian hornet is reported to be capable of destroying up to 30 percent of a bee colony in just a couple of hours (2). Asian hornets may also enter a honey bee hive to raid a colony (5) after attacking the honey bee guards (2). Although the worker hornets eat part of the prey themselves, most of the captured insects are decapitated, have their legs and wings removed, and are then formed into a pulp to be fed to the developing hornet larvae back at the nest (2).

Formed of six or seven separate layers known as ‘cell cakes’ and wrapped in an exterior ‘envelope’ (2), the nest of the Asian hornet is a very large (3) (4) and round structure (2) (4), and is usually slightly taller than it is wide (2). Progressively growing in size from spring until autumn, the nest can measure between 60 and 90 centimetres in height and between 40 and 70 centimetres in diameter in some parts of the species’ range (2). The Asian hornet’s nest is made up of as many as 17,000 individual cells (2), with each nest containing as many as 1,000 or more individuals hornets (2) (7). Each nest usually has just one entrance about half-way up the side, protected by a papier-mâché awning (2).

The Asian hornet has a relatively long period of seasonal activity (6), being active from about April to November, with a peak in August and September (3). At this point, fertile males will seek out young virgin queen hornets with which to mate (2). Colony activity tends to stop as winter sets in, at which time the males and workers die, and the mated queens enter hibernation (4). The average lifespan of a worker Asian hornet is only about 30 days during the summer, and about 55 days in warm spring weather (2). The queens over-winter either on their own or in groups, sheltering in cavities underneath tree bark, in plant pots or in any small, well-insulated crevice (2) (3).

Early spring sees the emergence of the mated Asian hornet queens (5), with some emerging as early as February (4), at which time the queens disperse to find a suitable area in which to nest, lay their eggs and establish a new colony (2) (4). Although little information is available to determine the exact start and end of the egg-laying period, it is thought that it may depend on temperature, with warmer weather potentially stimulating early laying activity, possibly as early as February (2). The first worker hornets begin to emerge in May, before the reproductive individuals emerge in the autumn (4). Large Asian hornet colonies are rapidly established, soon numbering several thousand individuals, many hundreds of which are mated queens. As the winter comes around and the colony dies, the cycle starts again as the mated queens seek out a place to over-winter (5).

The Asian hornet is not generally aggressive towards humans (2) (9), and in France is known to be predated by a variety of birds, particularly woodpeckers, jays and tits, which are seen pillaging nests and eating hornet larvae before the winter sets in (2).

The Asian hornet is not considered to be a threatened species, but is an invasive one, having established itself outside of its natural range in France (2) (9) and South Korea (7). After becoming established in South Korea in 2003, the Asian hornet has since spread northwards at a rate of between 10 and 20 kilometres per year, and in just seven years has become the country’s most abundant hornet species (7).

Given that it is a major predator of honey bees, the Asian hornet’s spread is of particular concern to beekeepers and the apiculture industry (4) (6) (9) (10), and this species is currently considered to be a significant threat (3), particularly as it appears to be having more of an impact on honey bee colonies in France than the native European hornet (Vespa crabro) has (2).

As well as honey bee colonies being left weak, vulnerable, low in numbers and often queenless following an Asian hornet attack (2) (9), the presence of this predatory species is also thought to have a potential indirect effect on honey bee health. With constant hornet activity around a honey bee hive, the bees have to spend much time and energy mounting a defence, which means foraging time is greatly reduced, leading to poor pollen reserves and the death of developing larvae (9). In addition to worries for honey bee keepers, a further concern is the decline of other insect species preyed upon by the Asian hornet, with many of these species being important in crop pollination (2) (6).

There are concerns that, as the UK has similar climatic conditions to France where the Asian hornet is currently thriving, the invasive species could enter its borders and become established (3) (9). There are multiple routes by which the Asian hornet could reach UK shores (9), with the principal pathways being flight across the English Channel (5) and importation of wood products which could contain hibernating queens (3) (5).

In the UK, the GB Non-native Species Secretariat (NNSS) is responsible for assisting with the coordination of plans to manage invasive non-native species in Great Britain (5), and is calling for any sightings of the Asian hornet to be reported to them immediately (9).

As the Asian hornet is not considered to be threatened, there are no known conservation measures currently in place for this species. However, it may need to be controlled in non-native areas, although all attempts to eradicate this species to date have proved unsuccessful (2).

There are some control measures currently being researched and tested in order to minimise the effect of the Asian hornet on honey bees and other insects. These include reducing the size of beehive entrances to prevent the hornets from getting in, hindering hornet activity by placing tall grass in front of hives, and killing hornet queens and destroying nests (2).

Find out more about the Asian hornet:

Find out more about the Asian hornet as an invasive species:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

  1. Species 2000 and ITIS Catalogue of Life (September, 2013)
    http://www.catalogueoflife.org/
  2. Mollet, T. and de la Torre, C. (Eds.) (2007) Vespa velutina - The Asian hornet. Bee Craft, 11-14.
  3. GB Non-native Species Secretariat (NNSS): Information sheet - Asian hornet (September, 2013)
    https://secure.fera.defra.gov.uk/nonnativespecies/index.cfm?sectionid=47
  4. López, S.,González, M. and Goldarazena, A. (2011) Vespa velutinaLepeletier, 1836 (Hymenoptera: Vespidae): first records in Iberian Peninsula. Bulletin OEPP/EPPO, 41: 439-441.
  5. Marris, G. (2011) The Asian hornet: Part 1. Bee Craft, 16-18.
  6. New, T.R. (2012) Hymenoptera and Conservation. John Wiley & Sons, Hoboken, New Jersey.
  7. Choi, M-B., Martin, S.J. and Lee, J-W. (2011) Distribution, spread and impact of the invasive hornet Vespa velutina in South Korea. Entomological Research, 41(6): 278.
  8. Villemant, C., Perrard, A., Rome, Q., Gargominy, O., Haxaire, J., Darrouzet, E. and Rortais, A. (2008) A New Enemy of Honeybees in Europe: the Invasive Asian Hornet Vespa velutina. XXth International Congress of Zoology, 26-29 August, Paris. Available at:
    http://inpn.mnhn.fr/gargo/Vespa%20velutina%20ICZ%202008.pdf
  9. Marris, G. (2011) The Asian hornet: Part 2. Bee Craft, October: 35-38.
  10. DAISIE (2008) Handbook of Alien Species in Europe. Springer, Berlin.