Oriental Hornet Found in Heraklion Venetian Walls

A nest of the Oriental hornet, Vespa orientalis, has been identified inside Heraklion’s urban area in 2026.
Researchers at FORTH’s IMBB are studying the species and its growing ability to exploit urban environments.
Walls, cracks, rooftops, abandoned buildings, food waste, and water can all provide suitable conditions for colonies.
Residents should never approach or attempt to remove an active nest themselves.

Heraklion has a new urban resident

Crete has never exactly struggled with creatures that appreciate sunshine. But researchers are paying increasing attention to one particular resident: the Oriental hornet (Vespa orientalis), a large social wasp that is already established in Greece and is increasingly being recorded in urban environments elsewhere around the Mediterranean.

A nest found inside Heraklion in 2026 provides a useful example of how well the species can adapt to the modern city.

The discovery, reported by Patris.gr and discussed by Ioannis Leivadaras, a laboratory technician at the Foundation for Research and Technology–Hellas (FORTH) Institute of Molecular Biology and Biotechnology (IMBB), highlights something easy to overlook: wildlife does not necessarily need pristine countryside to thrive.

Why the Venetian Walls are useful hornet territory

Heraklion’s Venetian fortifications contain exactly the kind of features that can provide shelter for a colony.

Cracks, cavities, and protected spaces inside walls can offer suitable nesting locations, while the surrounding urban environment supplies other necessities: food, water, and warmth.

The same principle applies to old or abandoned buildings, roof spaces, tiles and other sheltered cavities.

The nest documented in Heraklion during 2026 was found in a wall within the urban area, providing a particularly clear example of the species’ ability to use built structures as nesting habitat.

Heraklion’s urban heat may be helping

Cities tend to retain more heat than surrounding rural areas because concrete, asphalt, and buildings absorb and release heat differently from natural landscapes.

For a heat-loving species such as Vespa orientalis, those conditions may extend periods of activity and potentially improve the survival of queens through milder winters.

Researchers stress, however, that temperature alone does not explain population changes. Food availability, water, suitable nesting sites, and the species’ ability to adapt to human environments all play a role.

The city is also a very good restaurant

Urban environments can provide remarkably convenient food supplies.

Adult hornets use sugary foods for energy, while the colony requires protein for developing larvae. That makes discarded food, ripe or fallen fruit, exposed pet food, open rubbish bins and food-service areas potentially attractive feeding locations.

Water is another piece of the puzzle.

Gardens, fountains, swimming pools and other places where water is available can contribute to the conditions needed by a colony.

This is one reason keeping food waste contained and avoiding exposed food around homes can be useful even when nobody has spotted a nest.

What does Vespa orientalis look like?

The Oriental hornet is relatively distinctive, although identification should not be based on size alone.

According to the FORTH/IMBB material published by Patris, the species has a reddish-brown body with yellow bands on the abdomen and yellow markings on the forehead between the antennae. Queens can reach approximately 35–40 millimetres, while workers are smaller.

That said, not every large wasp seen in Heraklion is necessarily Vespa orientalis.

Correct identification matters, particularly when dealing with a nest.

Should people be worried?

This is where a little perspective is useful.

The presence of Vespa orientalis does not automatically mean that people are in immediate danger. The species generally becomes defensive when its nest is disturbed, and the greatest concern is therefore an active colony close to homes, workplaces or heavily used public spaces.

As with other stinging hymenopterans, however, stings can produce serious allergic reactions in susceptible people. Severe allergic reactions can include swelling of the face or throat, breathing difficulties, dizziness, and a drop in blood pressure, and require immediate medical attention.

So the sensible rule is remarkably simple: do not poke the hornet nest.

What should you do if you find a nest?

Do not spray it, hit it, block its entrance, or attempt to remove it yourself.

An active colony can become defensive when disturbed, increasing the risk of multiple stings.

Instead:

Keep children and pets away from the area.
Keep your distance from the nest.
Do not attempt DIY removal.
Contact the appropriate local authority or a qualified pest-control professional for assessment and removal.
If someone is stung and develops breathing difficulty, swelling of the face or throat, dizziness or other signs of a severe allergic reaction, seek emergency medical assistance immediately.

The same advice applies whether the nest is in a garden, building, wall, or other part of the urban environment.

A particular problem for Crete’s beekeepers

There is another reason researchers and beekeepers are watching Vespa orientalis closely.

The Oriental hornet can prey on honey bees (Apis mellifera), making established colonies a concern for beekeeping, particularly during periods when hornet activity is high.

This is not simply a question of whether an occasional hornet flies through someone’s garden. Large, established colonies can put additional pressure on nearby honey-bee colonies.

FORTH’s IMBB is studying Vespa orientalis through its Molecular Entomology Laboratory, with research focused on understanding the species’ biology and developing more effective, selective and environmentally friendly ways of managing it.

The hornet’s annual timetable

The species follows a seasonal colony cycle.

In spring, a fertilised queen emerges from winter shelter and establishes a new nest. During summer, workers take over foraging, larval care and nest expansion. By autumn, the colony reaches its mature stage and produces new reproductive individuals, including queens and males.

As winter arrives, the old colony’s cycle ends while newly fertilised queens shelter through the colder period and can establish new colonies the following spring.

That seasonal pattern is one reason sightings and activity can become particularly noticeable toward the warmer part of the year and into autumn.

The bigger picture: Crete’s cities are changing habitats too

The Heraklion discovery is interesting for a reason that goes beyond one hornet nest.

Cities are not biologically empty spaces. They contain food, water, heat, and thousands of artificial cavities that can sometimes be used by species that once depended more heavily on natural habitats.

The Oriental hornet is already established in Greece and has also expanded its presence in parts of southern Europe. Official and scientific sources document its presence in areas of Italy, Spain and France, among others.

For Crete, the lesson is not to panic every time a large wasp flies past the balcony.

It is to understand what is happening, recognise that an active nest needs professional handling, and remember that the island’s increasingly warm urban environments can create opportunities for species that are exceptionally good at adapting.

Argophilia’s report is based on reporting and expert information published by Patris on November 13, 2026, including material from Ioannis Leivadaras of FORTH/IMBB. Readers can consult the original report for the full expert contribution and photographs.

Oriental Hornet Found Inside Heraklion: Why Vespa orientalis Is Moving Into the City