The discovery of yellow-legged hornet nests in Auckland is frightening.

There have been five confirmed detections to date. Two of these were small nests, more than a kilometer apart, which suggests there are likely more in the region.

Why should we worry? This hornet is a serious concern for all New Zealanders. Yellow-legged hornets are aggressive predators and can become highly abundant. They threaten people’s health, biodiversity and especially honey bees.

The yellow-legged hornet (Vespa velutina) was accidentally introduced into France in 2004. It then spread rapidly, at around 100 kilometres per year, and was established across France by 2017.

The hornet is now well established in Spain, Portugal, Germany and other European countries. It was first detected in the UK in 2016, and its predicted range extends as far north as Scotland. Their success in Europe suggests they could thrive across much of New Zealand.

In some European areas, densities of up to 13 nests per square kilometre have been recorded, with mature nests housing several thousands of workers. Some even reach up to 13,000 individuals.

People can die from hornet stings. Yellow-legged hornets will aggressively defend their nests and........

© The Conversation