Spot, Approach, Destroy: Dealing with Yellow-legged hornet Nests

Human-Height Nests: Nests found at human height are relatively easier to manage. They can be encased in multiple plastic bags or containers and then frozen at -20°C (-4°F) for 48 hours, ensuring the hornets inside are killed.

However, many nests are located at higher elevations and are more challenging. Accessing these might require techniques such as pruning, telescopic poles, or even lifting platforms to reach the nest and apply a solution to exterminate the hornets. Regardless of the nest’s location, it’s crucial to engage specialized operators for the eradication. Attempting to destroy the nest alone is strongly discouraged.

Non-Chemical Destruction Methods:

• Microwave Radiation: This method kills hornets without the use of chemicals, ensuring no harm to other species. The dead hornets and larvae can be safely consumed afterward. However, this technique was abandoned due to its challenging implementation, potential harm to nearby species and humans, and high costs.
• Lethal Temperature Exposure: This method doesn’t leave any toxic residues and poses no threat to humans or other species. It’s still under experimentation and doesn’t affect hornets outside the nest during treatment.
• Aspiration: This involves vacuuming the nest until it’s empty, then crushing the bag to kill the hornets, either by pressing or drowning them.
• Shotgun Shooting: Although this method doesn’t ensure the total destruction of the colony, it has been used by some as an unconventional approach.

Chemical Destruction Methods:

• Injecting pesticides, such as permethrin and its derivatives or pyrethroids, is a common method. This can be achieved using various techniques, like poles for internal destruction, placing meatballs laced with the chemical in front of hives, applying drops directly on trapped hornets, or even using paintball shots aimed at the nests. However, these techniques can harm the environment as they might expose other insect species and birds to the pesticides, especially if they consume the dead hornets. It’s essential to limit the exposure by removing the nest from the environment within 48 hours after treatment. Pesticide injections are generally reserved for larger, high-altitude nests.
• Other tested injection products include:
  –Sulfur Dioxide (SO2) Injection: This isn’t recommended due to its irritation properties. When it comes into contact with mucous membranes, it turns into sulfuric acid, causing eye and respiratory irritation.
  –Diatomaceous Earth Injection: A white powder that covers and quickly kills the hornets. It has an abrasive action that obstructs the hornet’s leg and wing joints and is highly absorbent, draining the hornet’s bodily fluids. The primary challenge is the same as other methods: the need for rapid nest removal to avoid exposing other species.

Please note that some of the chemical methods mentioned here may not be permitted in all countries. Expert nest removers will be well-versed in local regulations and will select the most appropriate and legal solutions for your situation.

Trojan Horse Technique:

An innovative approach involves using hornets to transport an active ingredient. The idea is to encase a pesticide in a matrix, only to be released when it reaches the nest due to specific conditions like temperature and salivary enzymes. One proposal, yet to be realized, is to transfer an entomopathogenic fungus (like Beauveria and Metharizium). Laboratory tests have been conducted, but field application is still pending.