Asian hornets 

The Asian hornet (Vespa velutina) is an invasive species which preys on honeybees, and is now widespread across mainland Portugal. It poses threats to both biodiversity and public health. Like other wasps, the life cycle is annual and begins in spring (February/March), when the young queen wakes up from hibernation. She searches for food based on the sugars she feeds on, seeking shelter in a hollow tree or in a building where she will begin laying eggs, thus founding the colony.

Identification: Asian hornets are smaller than native hornets, with a predominantly black/dark brown body, a yellow abdominal stripe, and yellow-tipped legs.

Key information on Asian hornet stings:

When they sting: they are most active during summer, particularly August and September. They are highly defensive of their nests, which are often found in trees, on roofs, or sometimes low to the ground.

Danger level: stings are similar in toxicity to native species but cause more pain, lasting swelling, and itching. They are not generally “killer” insects, but they are dangerous to allergic individuals and animals.

Symptoms of reaction: watch for severe swelling, difficulty breathing, dizziness, faintness, or hives, which indicate a potential anaphylactic shock.

What to do if you or your pet is stung:

• Wash the area with soap and water to prevent infection.
• Apply ice or a cold compress to reduce pain and inflammation.
• Use antihistamine creams or take pain relievers, if needed.

When to seek help: Seek immediate medical attention if you experience severe symptoms, or if you receive multiple stings, even if you are not known to be allergic.

What you can do

• Check for nests: large, pear-shaped nests, often high in trees, but also in sheds, hedges, or under eaves.
• Trim vegetation:  prune hedges and trees to reduce potential nesting spots.
• Manage waste: keep all bins tightly sealed and ensure garbage bags are tied to prevent leaks that attract hornets.
• Clear food sources: clean up fallen fruit in your garden and promptly remove pet food bowls.
• Remove water sources: eliminate stagnant water sources, such as uncovered water tanks, that may attract them, especially near swimming pools. 
• Target queen hornets: in spring (between February and May) set up selective monitoring traps (that allow smaller insects to escape (5mm holes) to protect native species) to catch queen hornets before they start a nest. A common effective mixture for spring trapping is 1/3 beer, 1/3 wine (to deter bees), and 1/3 red fruit syrup/jam.
• Report a nest or sighting as soon as possible: if you find a nest, do not attempt to destroy it yourself, as disturbing it can cause mass attacks. If you have access to the Cidadão Óbidos App, you can report it directly. Also you have the STOPvespa platform (Vespa Velutina – Cidadão Registe aqui o avistamento de um ninho ou vespa asiática – Responder – Open in browser – fill out the form. Or you can contact a private professional pest control service.