Asian hornets: how high-tech tracking helps beekeepers protect bees

Asian hornets are making life increasingly difficult for beekeepers in Germany and across Europe. They systematically prey on bees, weaken entire colonies and, in doing so, also threaten the pollination of fruit trees and wild plants. In Alsace, one beekeeper is demonstrating how modern technology can be used against the insect invasion – using methods that sound more like espionage than traditional beekeeping.

Why the Asian hornet is so dangerous to bees

The Asian hornet is considered a nightmare for bees for good reason. It does not hunt at random but follows a clear strategy. Workers hover outside hive entrances, waiting for honey bees to fly in or out.

When a hornet strikes, the outcome is brutal for the bee: its head is removed and the abdomen is usually discarded. The protein-rich thorax is taken as food for the developing young in the nest. A single hornet can kill dozens of bees each day.

The constant siege outside the hive means foraging bees barely dare to fly out – striking at the very heart of a bee colony.

Eventually, many bees no longer venture outside the hive. Colonies collect very little nectar and pollen, while their stores diminish. This is particularly devastating in late summer and autumn, when bees should be preparing for winter. If food reserves remain too low, an entire colony may die over winter.

A beekeeper turns to radio technology against hornets

A beekeeper in the French department of Haut-Rhin, close to the German border, was unwilling to accept this situation. Rather than merely setting traps or reporting nests, he has developed an approach that tackles the problem at its source: the hornets’ nest.

His aim is to locate the original first nest, where the queen raises her first workers after winter. Destroying this so-called primary nest halts the development of an entire hornet colony.

A miniature transmitter on the hornet

The beekeeper’s method is surprisingly straightforward yet effective. First, he catches a hornet near his hives. He then briefly sedates the insect with gas, such as gas from a small cartridge, so that it remains still.

He next attaches a tiny radio transmitter or circuit board to the insect’s back. These transmitters are exceptionally light, allowing the hornet to continue flying normally. Once it has recovered, he releases it and begins tracking it.

Using a rake-shaped antenna linked to his smartphone or a portable receiver, the beekeeper follows the signal. The closer he gets to the hornet, and therefore to the nest, the stronger the audible or visual signal becomes.

The passive victim becomes the hunter: the beekeeper uses a marked hornet as a living trail to the hiding place of the entire colony.

A thermal camera reveals the nest

To make the final stage more reliable, the beekeeper also uses thermal-imaging equipment. With binoculars that reveal heat sources, he scans shrubs, hedges and buildings. Hornet nests are generally noticeably warmer than their surroundings because many insects are active inside.

This makes it possible to find the nest even when it is well concealed, for example high in a tree or inside an outbuilding. Once the hiding place has been identified, many beekeepers notify the relevant authorities or specialist pest controllers, who can remove the nest in a controlled manner.

Why the first nest matters so much

Asian hornets often build two nests during the year. In spring, the queen creates a smaller, sheltered primary nest, in which only a few workers initially emerge. Once the colony has grown stronger, a larger secondary nest containing thousands of insects follows in summer.

It is this second nest in particular that causes the greatest damage. Countless workers set out from it towards apiaries and fruit orchards. Individual beekeepers have little chance against such a fully developed colony.

Destroying the first nest early, by contrast, tackles the problem at its root. The queen dies, along with the entire future colony. As a result, thousands of workers that would otherwise attack bees and other insects later in the year never emerge.

Every removed primary nest means tens of thousands fewer hornets the following year – and far calmer apiaries.

Beekeepers report that attacks on nearby hives often decline almost immediately after a primary nest is removed. In regions where several nests have been located and eliminated early, colony losses sometimes stabilise considerably.

What beekeepers and garden owners can do against hornets

The high-tech method involving transmitters and thermal optics is demanding and is not realistic for every hobby beekeeper. Even so, several basic measures can reduce the risk.

• Position apiaries in sunny, open locations, where hornets find it harder to use cover while hovering.
• Narrow hive entrances when hornet pressure is high, so that bees can defend them more easily.
• Do not leave sweet drinks, fallen fruit or leftover feed directly beside hives.
• Report suspicious nests early to the local council, fire service or nature conservation authorities.
• Build networks with beekeepers in the area so that sightings and discoveries can be shared quickly.

Some local authorities already operate reporting points specifically for Asian hornets. Specialists assess whether a nest should be removed and how this can be done safely. Private individuals should not intervene themselves, as the insects defend their nests very aggressively.

How the spread affects Germany

The Asian hornet originally comes from East Asia and reached Europe through international goods transport. It has spread extensively in France over recent years, and has now been recorded in many parts of Germany.

The insects favour mild areas, but adapt remarkably well to different habitats. Wine-growing regions, river valleys and towns offer plentiful food sources and nesting sites. This increases the pressure on honey bees, as well as wild bees and other pollinating insects.

This specialisation is precisely what makes the Asian species so problematic. While the native European hornet is regarded as beneficial and eats many pest insects, the invasive species focuses heavily on honey bee colonies.

Opportunities and limits of high-tech tracking

The method described shows how inventive beekeepers now have to be to protect their colonies. Radio technology, thermal cameras and precise tracking have more in common with wildlife research or police surveillance than with conventional farming.

Such techniques require money, time and experience. They are therefore most suitable for areas where pressure is especially high or where many professional beekeepers operate. The approach appears practical when several businesses cooperate and share the equipment.

It remains unclear how the technology will develop further. Even lighter transmitters, automatic receiver stations or apps that analyse signals and create maps of suspected areas are conceivable. Combined with public reporting systems, these could allow authorities to respond more quickly when new areas become problem zones.

At the same time, conservation questions arise. Invasive species need to be controlled, but blanket control campaigns should not harm native insect populations. Anyone reporting nests or arranging for their control needs trained personnel who can reliably distinguish between species.

For beekeepers, the Asian hornet remains a serious concern. High-tech nest tracking may look spectacular, but it cannot replace daily precautions at the apiary, resilient colony management and close cooperation with neighbours, local authorities and public bodies. One thing is clear: the earlier a nest is found, the greater the chance of protecting bees and pollinators in the region in the long term.