The Japanese giant hornet (Vespa mandarinia japonica) is terrible. It can completely destroy a bee colony. The honey and bee larvae are also taken to feed the hornet's larvae.

Japanse honey bee's protective behaviors

Japanese honey bees can protect their colony against giant hornets. As a hornet enters the hive, a mob containing hundreds of honey bees surrounds the hornet, forming a ball, completely covering it and preventing it from reacting effectively.

The bees violently vibrate their flight muscles in much the same way as they do to heat the hive during cold conditions. This raises the temperature in the ball to the critical temperature of 46 °C (115 °F).

In addition, the exertion of the honey bees raises the level of carbon dioxide (CO2) in the ball. At that concentration of CO2, the honey bees can tolerate up to 50 °C (122 °F), but the hornet cannot survive the combination of a temperature exceeding 46 °C (115 °F) and a high carbon dioxide level.

However, they cannot protect their colony when many giant hornets attack them at the same time. They will not fight giant hornets to the end and instead choose to abscond. It seems that giant hornets destroy many wild Japanese honey bee colonies.

One day in September, giant hornets attacked my observation hive. The colony was invaded, and the bees absconded.

How to save bees

I can effectively protect my bees from hornet attacks because my pile box hive is designed to prevent hornets from invading.

The entrance is not high enough for giant hornets to invade. It is best if it is made of metal because giant hornets will chew the entrance in effort to expand it, so that they can gain access to the hive. However, after failing to expand the entrance, giant hornets eventually will give up after a few days.

Wild beehives are often attacked by giant hornets. In those cases, the entrances are wide enough for giant hornets to enter the colony.

So, a metal mesh is an effective way to save wild beehives.

Glue trap for giant hornet

The giant hornet has a habit of attacking bees as a group. You can use this habit to capture giant hornets with a glue sheet trap easily.

First, capture a giant hornet and put it on a glue sheet when giant hornets are attacking your bees. Then, put it near the beehive. The pheromone emitted by the captured hornet attracts other giant hornets, thus leading them to be entrapped on the glue sheet as well.

Western honeybees

By the way, the giant hornet is much bigger problem for Western bees because they are not equipped to protect their colony from the hornet.

An individual giant hornet can kill forty Western bees a minute while a group of 30 hornets can destroy an entire hive containing 30,000 bees in less than four hours. This is why Western bees cannot live in the wild in Japan.

As a result, the giant hornet protects the ecosystem and habitats of Japanese honeybees from the non-native Western honey bee.