Vespa-Watch

Vespa-Watch is the Flemish hotline for reporting nests and individuals of yellow-legged hornets.

See the Dutch version of this website to report nests and find up-to-date information on nest eradication, reported nests, etc.

Why are yellow-legged hornets harmful?

The yellow-legged hornet (Vespa velutina) is a wasp species from Southeast China. Since 2016, the species has also been present in Belgium. It is an ‘invasive alien species’:

• The species did not originally occur here, but is now rapidly increasing in number and spreading throughout Flanders.
• It attacks honey bees and other native insects that pollinate our flowers and plants.

Check the What is the issue? page for more info.

What can you see throughout the year?

• In spring, one yellow-legged hornet queen builds a new nest. This is the size of a ping-pong ball and can be found in a sheltered place, such as under a canopy or in a pen.
• From June onwards, the first workers hatch and the nest grows further, to the size of a small football. Now you can start tracking nests using wick bait stations.
• From August onwards, 70% of all nests move to higher places due to lack of space. A second nest is then built high in the top of a tree or on a facade. The entire colony moves to this second nest, and the first nest is abandoned.
• At the end of summer, a nest can reach a diameter up to 1 m.
• In autumn, nest yellow-legged hornet nests become more visible.
• In winter, drones and workers die. Only queens seek a wintering place. Exceptionally, you may encounter a yellow-legged hornet queen inside your house, having awakened early. All nests are inactive, there are no hornets inside. They no longer need to be eradicated.

How do I recognize a yellow-legged hornet?

Check the identification page to identify individuals, distinguish them from other wasps and identify their nests.