The yellow-legged hornet (Vespa velutina) originating from Asia is an invasive species that is particularly dangerous to honey bees. In Europe, it was first detected in France in 2004. Over the following years, it spread to other countries, including: neighboring Poland, such as Germany, Slovakia and the Czech Republic. In October, it was spotted in Poland - in Wielka Wieś near Krakow, and later also in the apiary of the AGH University of Science and Technology in Krakow.
“I think we will find more of these nests.”
The nest eliminated in Małopolska was brought to the Wrocław University of Environmental and Life Sciences a week ago, where it is being researched by Prof. Paweł Migdał and his team.
In an interview with PAP, the scientist pointed out that the nest was located in a tree, which is typical for this species of hornet. I think we will find more of these nests. They are often built on the tops of trees, which makes them invisible until the leaves fall in autumn, the scientist said.
Experts from Wrocław have already carried out a biological assessment of the first yellow-legged hornet nest in Poland. It contained eggs and larvae, indicating that the hornets living there were still feeding. The workers foraged and fed these larvae, so the nest would continue to develop. Considering our climatic conditions, it was quite a large nest. It was inhabited by about a thousand workers, who were responsible for supplying the nest with food resources, and several dozen males and females - said Prof. Almond.
He added that the young females managed to leave the nest to establish new nests after wintering. Young females appear in the nests in September. The longer and warmer the autumn, the better for them, because it increases their chances of survival in our climate, the scientist said.
They hibernate to become active again
After the females leave the nest, they look for shelter for the winter. This may be a hiding place underground, in the attics of houses or in warehouses for various materials. Insects look for places where they can protect themselves against low temperatures and excessive humidity. There they hibernate to become active in the following season as temperatures rise.
Females that survive the winter build new nests - each of them their own. The problem with this species is that it does not need sheltered areas to build a nest, like the European hornet, which builds nests in gazebos and other enclosed spaces, for example. The yellow-legged hornet builds nests in trees, which makes it even easier for it to function in the environment - said Prof. Almond.
The first nest built by the female after wintering is small, the so-called primary (satellite). She must feed the first workers there, which will later build a proper nest. Insects expand their nests throughout the season. The yellow-legged hornet's nest is much more durable than the European one, which is delicate and more fragile, the professor said.
Invasive yellow-legged hornet
The yellow-legged hornet is a very invasive species. To show the scale of this invasiveness, it is enough to point out that the European hornet releases about 50 young female queens from the nest, and the yellow-legged hornet releases an average of 150, and in highly favorable conditions, which do not occur in our country, about 500, and each of these mothers, young queens, is a future nest - said the scientist.
The Asian hornet, commonly known as the Asian hornet, feeds on, among others: honey bees and other pollinators. In addition to the fact that this hornet kills honey bees, its presence also causes bees to stop working in apiaries. In the case of the European hornet, the bees see that there is a threat, but in a sense they continue to work. However, the yellow-legged hornet is a completely new threat to them, the scientist said.
