Vorarlberg removes two Asian hornet nests with steam

A specialist company removed two Asian hornet nests from trees in Dornbirn using hot steam on Thursday, ORF Vorarlberg reported. The nests were about 25 metres above the ground, making the operation difficult.

The nests were found in Dornbirn-Wallenmahd and Kehlegg after the Vorarlberg beekeepers’ association tracked hornets fitted with small radio transmitters. The nests, usually 60 to 70 centimetres across, are often hard to spot high in tree crowns.

The company used telescopic carbon-fibre poles to pump steam into the nests. The heat killed the hornets and their brood in about 20 to 25 seconds, without using poison. The method has also been used successfully in Tyrol this year.

Asian hornets are no more dangerous to people than native hornets, which generally sting only when their nest is threatened. But the introduced species poses a serious risk to local ecosystems because it catches honeybees and wild bees to feed its young. A nest can contain 1,500 to 2,000 hornets and produce hundreds of new queens each year.

The nest remains were handed to inatura Erlebnis Naturschau Dornbirn for examination to determine whether young queens and male hornets had developed. The state of Vorarlberg is covering the removal costs.

To locate the nests, specialists first watched hornets at beehives and tracked their flight directions and return times to narrow down the search. They then attached transmitters to selected hornets and followed them. A drone with a thermal imaging camera was also used, but the nests were difficult to distinguish from their surroundings.