The Vespa velutina, widely recognized as the Asian hornet or yellow-legged hornet, is an insect species native to Southeast Asia. This hornet has emerged as an invasive species across various global regions, particularly in Europe. It was first detected in France in 2004 and has since established itself.
Physical Identification
The Asian hornet can be identified by several distinct physical characteristics. Its body is predominantly dark brown to black, with a largely dark abdomen. A distinguishing feature is a broad, orange-yellow band on the fourth abdominal segment. The legs are dark brown, but their tips are conspicuously bright yellow. Worker hornets typically measure around 20 millimeters in length, while queens can reach up to 30 millimeters. The head is black with an orange or yellow face.
Distinguishing the Asian hornet from the native European hornet (Vespa crabro) is important. The European hornet is generally larger, with queens measuring up to 35 millimeters and workers between 18 to 23 millimeters. Unlike the Asian hornet, the European hornet has a yellow face and a largely yellow abdomen with brown stripes, not a single prominent orange band. Its legs are reddish-brown without the bright yellow tips seen on the Asian hornet.
Ecological Impact
The presence of Vespa velutina has environmental consequences due to its predatory behavior. This hornet is a predator of other insects, particularly honeybees (Apis mellifera), which constitute a significant portion of its diet. Hornets hover outside beehive entrances to intercept returning forager bees. This predation stresses honeybee colonies, disrupting their foraging.
Sustained predation can weaken or destroy honeybee colonies, leading to losses in some areas. A decline in honeybee populations can affect agricultural pollination services for crops. Vespa velutina also preys on a wide range of other beneficial native pollinators, including hoverflies, solitary bees, and other social wasps. This broad predation can lead to a reduction in local insect diversity within wild ecosystems.
Human Interaction and Safety
Vespa velutina is generally not aggressive towards humans unless its nest is disturbed or it feels threatened. Hornets will actively defend their nests, and approaching too closely can provoke a defensive response. Studies indicate that workers may show defensive behavior when a person is within approximately 3 meters of a nest, and this aggression can increase with sudden movements. The sting of an Asian hornet is comparable in pain to that of other hornets or wasps.
As with any insect sting, there is a risk of a severe allergic reaction, known as anaphylaxis, in individuals who are susceptible. Multiple stings can increase the severity of symptoms, and in rare cases, hospitalization has been reported due to anaphylactic shock. The most effective safety measure is to maintain a safe distance from hornets and their nests and to avoid any actions that might provoke them. Rapidly moving away, ideally for at least 10 meters, can help reduce the number of attacking hornets if a nest is disturbed.
Distribution and Management
Native to Southeast Asia, Vespa velutina began its invasive spread into Europe after its accidental introduction to France in 2004, likely via imported pottery or plants. From France, the species rapidly expanded its range, establishing populations in countries such as Spain, Portugal, Belgium, Italy, Germany, and the United Kingdom. The spread rate in France was estimated at approximately 78 kilometers per year. More recently, confirmed sightings have been reported in North America, including Georgia, USA, in 2023, prompting monitoring efforts in surrounding states.
If a suspected Asian hornet is sighted, it is important not to attempt to kill the hornet or destroy a nest personally due to the risk of stings and the potential for confusion with native species. Instead, the primary course of action is to report the sighting to relevant authorities. In many regions, this involves contacting a national invasive species reporting body or a state’s Department of Agriculture. Providing a clear photograph of the insect, taken from a safe distance, along with location details, can greatly assist official identification and subsequent management efforts.