Asian hornet, also called killer wasp, known scientifically as velutin vespa, becomes more active as heat rises and threatens both people and wildlife once again. It arrived in Spain about twelve years ago and spread rapidly during the early years. It is now found in most regions, with only scattered pockets remaining free of this dangerous insect, which can be deadly if it bites or stings. While it seems strongest in the northern peninsula, its presence is now felt across the country.
Between 2019 and 2021, Spain recorded more fatalities related to encounters with these hornets, totaling seven deaths in that period. In 2019 there were three additional fatalities and three more in 2020, despite quarantine measures. Galicia and Asturias accounted for all the fatalities, underscoring the zones most affected by this invasion.
All of these deaths occurred when individuals inadvertently found themselves close to Asian hornet nests. This species is highly territorial and will defend its nest aggressively if provoked.
It is estimated that these hornets account for a large share of stings in areas where they are most common. About 3% of the population experiences allergic reactions. Their venom is comparable to that of other wasps and bees, and the annual death toll is estimated at about 0.08 per million people, equivalent to three or four deaths per year in the country, according to Berta Ruiz, chair of the Hymenoptera Allergy Committee of the Spanish Society of Allergology and Immunology.
How far has this hornet actually spread across Spain?
According to the portal avispasiatica.org, which tracks the presence of this species in Spain, by 2029 the Asian hornet is expected to have colonized nearly the entire peninsula, including Ceuta, Melilla, and the Balearic Islands. The Canary Islands would reportedly remain outside of the invasion.
Experts disagree on the pace and extent of expansion along the peninsula. Some say the insect already occupies most regions, while others argue it remains largely confined to the north, with sightings in Zamora and parts of Madrid. Isolated individuals are seen frequently, but firmly established colonies may still be concentrated in particular areas.
Alfonso Balmori, a biologist with the Junta de Castilla y León, noted that the prevailing view years ago was that the hornet would colonize almost the entire peninsula, though he acknowledged the assessment is nuanced. He pointed out that the species has strict climatic limits on breeding ranges.
He added that even where specimens appear in many areas of the peninsula, they do not always establish due to climatic constraints, especially harsh winter frosts in the northern plateau and prolonged drought in the southern plateau. He suggested that the species may not expand much further than it already has.
The Community of Madrid has echoed this assessment, stating that no Asian hornets have been detected there. They cautioned that plateau regions with hornet presence are unlikely, particularly noting that there has been no confirmation of entries from the Cantabrian coast or Galicia. Residents are reminded that sightings can occur outside these zones as monitoring continues.
Threat to bees
The killer wasp poses a serious risk to bee populations already stressed by pesticides and climate change. It has the ability to devastate hives by predation and competition.
Research from CREAF suggests that a single hornet can capture between 25 and 50 bees per day. Its larger size allows it to intimidate and kill bees with a powerful bite, then carry body parts and larvae back to the nest to feed. When workers disappear, the hive is vulnerable and the honey collection can be disrupted.
The hornet’s rapid spread in Spain is driven by a strong capacity to reproduce and disperse. A single queen can produce a nest with thousands of cells and potentially hundreds of new queens each year, explaining the swift population growth.
Reports indicate a steady north-to-south expansion at about 100 kilometers per year. The frontier of its advance is described as reaching toward southern Zamora and some remote Extremadura areas, though people continue to spot hornets beyond these zones.
Two years ago, the Balearic Islands were highlighted as the first European region to attempt eradication of the killer wasp. Yet even there, containment remains challenging, and cautious measures are advised.
Caution is advised, as Asian hornets may still be present in Mallorca’s Serra de Tramuntana or other hard-to-reach areas. Authorities emphasize vigilance, noting that a controlled situation in one region does not guarantee safety elsewhere.
How is the killer wasp described?
The Asian hornet measures 17 to 32 millimeters in length. It features a dark thorax and abdomen with a yellow trim on the posterior abdominal segment. The head is dark with a yellow or orange face, and legs are brown with yellow-tipped ends.
Nests are often large and spherical, with an entrance on the side. They are typically built high in trees, like alder, chestnut, walnut, apple, cherry, or eucalyptus, and occasionally on buildings, stairs, or barns in sheltered locations.
Ongoing research explores biological control methods to challenge this species. Until effective solutions emerge, interception and nest removal remain the primary means of control.
What to do if stung?
Stings are extremely painful but generally not more dangerous than those from common wasps. Local symptoms include pain, redness, and swelling, which usually subside within a few days.
The affected area should be washed with soap and water and cooled with ice or cold compresses. Early on, heat can sometimes neutralize certain venom components.
In allergic individuals, symptoms can escalate to widespread itching, fever, low blood pressure, breathing difficulties, heart or nervous system problems, swelling of the throat, or fainting. In cases of multiple stings, venom load may be high and systemic symptoms can appear even without prior allergy.
If general symptoms develop after a sting, stay calm and seek immediate medical care, as signs can indicate a serious reaction such as anaphylactic shock.
It is advised to contact emergency services or visit a medical center promptly if allergic symptoms or severe reactions occur.