Asian Hornet
The Asian hornet, whose Latin name is Vespa velutina, is an insect of the Vespinae family. As its name suggests, it is native to Asia, mainly present in the Continental climates of India, China or Afghanistan.
The most commonly observed Asian hornet in Europe is the Vespa velutina nigrithorax. This subspecies was introduced in France in 2004 and developed very quickly in the rest of Europe due to its rapid reproduction (one nest not destroyed gives an average of 4 other nests the following year) and the absence of predators apart from a few birds.
The Asian hornet is recognizable by its yellow legs, black thorax, dark colour and dark abdomen surrounded by a yellow-orange ring marked with a black triangle.
The queen.
The queen is distinguished by her larger size, it can measure up to 3.5 cm. She is the founder of the colony, which she established between February and the end of June. During the first few weeks, the queen lays one egg a day or so and spends its time feeding the larvae, which will become the first individuals called first caste workers. From the middle of June for the earliest nests and towards the beginning of August for the late nestings, the queen has enough workers to feed her, she then spends all her day laying eggs. At the end of the summer, the queen lays male and female sexuals (called gynes). These are the future founders of new nests. They will spend the winter in a protected place, in which they will be in diapause (principle consisting in decreasing the intensity of their metabolic activity). Those who survived, will leave the following spring to found their colony.
The worker.
The workers measure between 1.4 and 2.8 cm on average. The first workers from the small cells developed by the founder will be smaller than the individuals to come. The larger the colony, the larger the individuals.
The adult hornet feeds on ripe fruit, nectar, plant foods rich in sugar or sap. But what makes it a threat to the ecosystem are the feeding habits of the larvae. Adults attack various insects, which they kill with their powerful mandibles. The victim is then cut up and chewed to make meatballs from which the larvae feed. The latter secrete a sweet, amino acid-rich liquid consumed by the workers and the queen. Their targets of choice? bees! They are easy prey whose hive access configuration is similar to a distributor for their deadly predator.
The Nest.
A nest can hold up to 3000 individuals. It is composed of chewed cellulose fibres and can measure up to one meter high. It is often aerial, in trees, under frames… But ground-level nests could be observed as well as opportunistic nests, located in attics, on urban furniture… Everything is possible as long as the necessary conditions are met.
The nest has an opening on the side. This is what distinguishes it mainly from the European hornet nests (Vespa crabro) whose entrance is located below. The nest of European hornets is also smaller in general, and never located on top of trees, that of the Asian hornet being able to perch several tens of meters.
Expansion and dangerousness of the asian hornet.
In Europe, the Asian hornet is an invasive and harmful species. In 2016 it was added to the list of invasive alien species of concern to the European Union.It was first observed in France in 2004 in Lot et Garonne, probably from containers of imported Chinese pottery. Since then, the entire territory and many neighbouring countries have been colonized, worrying beekeepers who see their hives ravaged by these predators.
The sting of the Asian hornet is no more dangerous than that of a wasp. It can be observed safely. However, there are three cases that can cause complications; Multiple stitches, a sting in the throat or a patient allergic to venom. In these cases we can then observe respiratory shocks or Quincke edema.
It is obviously not recommended to approach less than 5 meters from a nest because the hornets could be aggressive.