Japanese giant hornet (Vespa mandarinia japonica) is terrible. It destroys bee's colony completely. The honey and bee larvae are also taken to feed the hornet larvae.
Japanese honeybees can defeat giant hornets. As a hornet enters the hive, a mob of hundreds of honey bees surrounds it in 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 in cold conditions. This raises the temperature in the ball to the critical temperature of 46 °C (115 °F).
In addition, the exertions of the honey bees raise 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 of 46 °C (115 °F) and high carbon dioxide level.
However, they cannot protect their colony when many giant hornets attack them at the same time. They do not fight with giant hornets to the end and abscond when they give up. It seems that giant hornets destroy many wild colonies of Japanese honeybees.
One day in September, giant hornets attacked my observation hive. The colony was occupied, and the bees absconded.
I can save my bees completely from the hornet because my pile box hive is designed to prevent it from invading.
The entrance is not high enough for giant hornets to invade. It should be made of metal because giant hornet bite the entrance and try to make the entrance larger. Giant hornets eventually give up in a few days.
Wild beehives are often attacked by giant hornets. In most cases, the entrances are wide enough for giant hornets.
So, metal mesh is effective in saving wild beehives.
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. Pheromone emitted by the captured hornet attracts other giant hornets.
By the way, giant hornet is much bigger problem for Western bees. They can not 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. It is why Western bees cannot go wild in Japan.
As a result, giant hornet protects the ecosystem and habitats of Japanese honeybees.