The specie of Asian origin that was introduced in Europe is the Vespa velutina nigrithorax, commonly known as the Asian hornet or yellow-legged hornet.
The Vespa velutina is essentially a predator of bees and other wasps, but, like Vespa crabro (European hornet), it also develop the colonies from a wide variety of other insects.
Find out about its characteristics in the following image:
The specie is diurnal and has an annual cycle.
Depending a lot, mainly on climatic conditions, this cycle starts from February to May, with the formation of primary nests by the foundresses.
Between July and October, there is the greatest predation of the hornets workers, mainly on bees, an activity associated with the growth of the typical secondary nests, often in tall trees.
In late autumn, early winter, the nests cease to be active and the new foundresses abandon them to hibernate in decaying tree trunks, rocky worms or even in the ground. While the founders have an annual longevity, the workers live between 30 and 55 days.
The nests are made of made from chewed cellulose fibers, with a rounded or pear shape, and lateral opening.
According to the Vespa velutina's life cycle, two types of nest are identified, whose differentiation we can assess according to the following criteria:
NATIVA only intervenes confirmed active Vespa velutina nests. It must take into account that:
- The Asian hornet is not considered to be more dangerous to humans than the European wasp.
- The presence of many wasps does not necessarily mean the presence of a nest, eg, they may be attracted to certain types of flowers (typically Callistemon and Hedera Helix) or to honeydews segregated by certain plants or insects such as aphids (in this case, spraying a tree/bush with soap and water can eliminate the aphid and wash away the attractive substances).
Once the existence of a Vespa Velutina nest is confirmed, and if you know that NATIVA has a contract with the municipality where it resides, you can report it to the Municipal Council, the Parish Council (which will forward the request) or directly to the NATIVA Association.
To do this, just send an email to ad@anativa.org with the following data:
- Parish
- Location (street/police number), GPS coordinates of the nest location (Google Maps pin)
- Dimensions (estimated height and size)
- Support where it is found: tree (if possible identify the species), floor, roof, wall, other
- Photography (always useful, especially when there are doubts)
- Applicant's name and contact (who reports the nest)
It must take into account that:
The destruction of nests must only be carried out by properly protected and instructed personnel!
As you can see in the image below, you will see that the nest has a signaling tape that demonstrates the completion of the intervention.
The intervention consists of injecting a food bait into the nest, which will eliminate the adult insects between approximately 24h/48h, with the complete process of eliminating the new insects (nymphs) at the end of 2/3 weeks.
The nest itself remains in place, but will degrade due to its inactivity and eventually fall.
It is possible to be confused with other insects of our Fauna, in particular Vespa crabro (European hornet), but this has a yellow coloration of the abdomen with black spots shaped similar to run-off paint.
The head is yellowish and its dimensions can surpass those of the Vespa velutina.
Discover the differences here