The relationship between bees and wasps, particularly large predatory hornets, is a conflict of survival where the wasp attempts to raid the bee colony for protein-rich larvae and honey stores. A single hornet can scout a hive and then recruit nestmates for a mass attack that can quickly decimate a colony, often by decapitating thousands of adult bees. To counter this destructive threat, honey bee colonies have evolved a layered set of defenses, ranging from individual sacrifice to architectural barriers and complex, coordinated group counterattacks.
Individual Defensive Actions
The first line of defense against an approaching wasp often falls to specialized guard bees stationed at the hive entrance. These older worker bees, whose venom is at its maximum potency, physically inspect all incoming traffic and attempt to intercept any perceived intruder. Guard bees position themselves on their back four legs, with their front legs raised, ready to engage an attacker.
If a wasp persists, the guard bee will attempt to bite, wrestle, and sting the predator to drive it away. Stinging is a last-resort action because the barbed stinger often remains lodged in the wasp’s exoskeleton, tearing away from the bee’s abdomen and leading to its death. This sacrifice neutralizes the threat or releases a potent alarm pheromone that mobilizes additional defenders. Foragers away from the hive use avoidance tactics, sometimes performing a distinctive body-shaking signal when a predator is spotted, which may deter an attack.
Architectural and Chemical Deterrents
Beyond the front-line fighters, the bees employ passive and chemical defenses that make the hive a difficult fortress to breach. One structural defense involves narrowing the hive entrance, a practice that limits the space a larger wasp can use to maneuver and attack. This effectively reduces the area the guard bees must patrol, giving the smaller bees a distinct advantage against a bulky intruder.
Bees also utilize propolis, a resinous mixture of plant saps and beeswax, as a versatile building and defense material. The bees apply this “bee glue” to seal cracks, smooth internal surfaces, and reduce the hive entrance size. Propolis acts as a chemical deterrent because its antimicrobial properties help maintain a sterile environment within the hive. It is also used to embalm dead invaders that are too large to remove, preventing decomposition and subsequent infection.
Coordinated Colony Counterattacks
The collective counterattack is a synchronized behavior used to overwhelm large, armored predators like the Asian giant hornet. The best-known example is “heat balling,” a strategy employed by certain species, such as the Japanese honey bee (Apis cerana japonica), which co-evolved with these large hornets. When a scout hornet enters the hive, up to 500 worker bees immediately swarm and form a tight, spherical mass around the invader, trapping it at the center.
Within this dense formation, the bees vibrate their flight muscles to generate heat, raising the core temperature of the ball. This sustained muscular activity elevates the temperature to a lethal range, typically around 46°C (115°F), which is fatal to the hornet. The bees can tolerate temperatures up to about 50°C (122°F), providing a narrow thermal safety margin that allows them to kill the wasp. The balling action also increases the concentration of carbon dioxide inside the ball, which further accelerates the hornet’s death.