Moses Lake, WA 98837, USA

Honeybee-killing hornet a concern in Washington

Staff Writer

COUPEVILLE — Washington State University and the Washington State Department of Agriculture are asking for the help of Washington residents to report sightings of the Asian giant hornet. The Asian giant hornet, also known as the Japanese giant hornet, is known for killing honeybees and can be dangerous to humans.

“Justin Schmidt describes it as the most intimidating and venomous insect in the world,” said Tim Lawrence, WSU Island County Extension director.

The Asian giant hornet can be from 1.5 to 2.5 inches in length, according to Lawrence. It is the largest hornet in the world.

“There are a lot of (insects) that look similar,” Lawrence said. “It is distinct in the head. It is very yellow. If you see a very large wasp and it has a yellow head, the WSDA would be interested in talking to you.”

The giant hornet is native to Asia. In Japan, they are a major problem. The hornet attacks honeybee colonies, killing the entire hive and eating the pupae and larvae, together known as the brood.

Giant hornet hives start in the spring when the queens inseminated in the fall emerge. They need carbohydrates to help establish their nest. Typically, the nest is in the ground, but they can also be found in the voids of walls. Around July, the nest has enough workers so that the queen no longer has to go look for food. She sticks to the nest and is able to concentrate on laying eggs.

About September, the queen begins to lay eggs for drones for mating that fall. Her diet goes from one of carbohydrates to protein. Protein is also needed for the drones and hornet larvae. Since the honeybee brood is high in protein, they are a target of the giant hornet.

The attack on a honeybee colony takes place in three stages: hunting, slaughter and occupation. Scout hornets are sent out to find honeybee colonies. The scout marks the colony with a pheromone which allows other giant hornets to find the hive.

When the scout returns to the beehive, it brings with it other giant hornets and the attack begins.

Thirty giant hornets can kill off a hive of 30,000 honeybees in three to four hours. After the hornets have secured the hive, they will occupy the hive until all the honeybee pupae and larvae have been harvested or have gone rancid. This final phase lasts 10 to 14 days. The honeybee brood is fed to the hornet’s larvae.

Japanese honeybees, which have to live alongside the giant hornets, have a different approach to dealing with the hornets than European honeybees. The Japanese honeybees see the hornet scout and draw it into the hive. As a massive unit, they completely engulf the hornet in a giant bee ball. The bees then wiggle and heat up the hive to within a few degrees of their heat limit. The heat slowly bakes the hornet scout alive. While some of the bees suffer shorter life spans as a result of the heat, the hive overall is safe from the giant hornet’s attacks.

European honeybees, which are used in the United States, do not recognize the giant hornet scout or its marking pheromone and allow their hive to be marked. When the invading force arrives, the bees attack, attempting to sting the invaders. The invading force is greatly outnumbered by the honeybees but has the advantage of size. The hornets position themselves at the entrance of the hive and bite the heads off of the bees as they come out of the hive. The giant hornets can wipe out a healthy, flourishing colony of bees in a matter of hours.

While the Japanese honeybees are better at dealing with the giant hornet, Lawrence said that they are not a good option to bring into the United States.

“It would not work well in our pollination system,” Lawrence said.

No one knows how the Asian giant hornet got to the United States.

“There is speculation that it could have come over on a cargo ship,” Lawrence said. “Someone might have purposely introduced them. We don’t know.”

So far, the hornets have only been spotted on the west side of the mountains, in the area approximately between Blaine and Bellingham, in Whatcom County. One farmer in the area has reported that his tractor was swarmed by yellow-faced hornets.

So far, no giant hornets have been spotted on the east side of the state.

“My wife was in Japan earlier this year,” Lawrence said. “We live on Whidbey Island. She said that if she didn’t know better, she would have said that she was on Whidbey Island. It (Japan) looked similar. The giant hornet is very well adapted to the west side. On the east side, it may not be as big of a problem. We don’t know yet.”

The Asian giant hornet only spreads into a new territory at the rate of 15 miles per year. Since the introduction of the giant hornets into Washington has only recently occurred, it is probable that there currently are not any in the east side of the state yet. The Washington State Department of Agriculture would prefer that the hornets not reach the eastern portion of the state at all.

“That’s why the WSDA is putting out so much effort right now,” Lawrence said. “It would be great if we were able to find all of them and destroy them. That’s a difficult task.”

The giant hornets pose what could be a major problem for raspberry and blueberry growers in Whatcom County. With the introduction of the giant hornet, beekeepers are going to have to make some decisions about the way they do pollination in the area.

“Beekeepers are going to have to make the decision of if they will trap the hornets or move the bees,” Lawrence said.

In Japan, beekeepers use sticky traps to catch the giant hornets. Once stuck, the hornets release a pheromone that attracts other giant hornets to the trap. They also have designed traps for small bee hives that trap the hornets as they come out the top of the hive. But after some use, the hornets figure out the trap and will not enter the hive. Instead, they will wait at the bottom of the hive and grab honeybees there.

The giant hornets are also dangerous to humans. They are usually not terribly aggressive when away from their nest. But that changes if their nest is disturbed or they are harvesting the brood from a honeybee colony. While the venom of the giant hornets is not as potent as that of a honeybee, they have seven times more venom. When stinging, they exert up to 225 percent more force than that of a honeybee.

In Japan, there are special bee suits that are slippery and are much thicker than the average beekeeping suit. The giant hornets can easily go through the average suit used by beekeepers in the U.S.

It is because of the hornets’ sting that the WSDA is advising Washington residents to report sightings of the hornets and not to try exterminating them. The WSDA has a special giant hornet website,, that gives information about the insect and allows sightings to be reported. They accept pictures of the hornet being reported for additional verification. Reports can also be made at 1-800-443-6684 or at

If someone stumbles upon an Asian giant hornet and is stung, Lawrence said not to panic.

“Get out of the situation as quickly as possible,” he said. “Because of the pheromone, others will find you because you have that mark. Don’t run in a straight line. Get in a building or vehicle.”

Because giant hornets can fly up to 25 miles per hour, it will be next to impossible to outrun them. Instead, elude the hornet by going around trees and bushes.

To temporarily deal with swelling or pain from being stung, an antihistamine and ice can be used.

“You always have to be concerned about anaphylactic shock,” Lawrence said. “Go to the emergency room as quickly as possible, especially if stung more than once.”