What to Know About Asian Giant Hornets

The world's largest hornets have been reported in the US, leaving many to question how dangerous these black and orange insects could be to our ecosystem.

The Asian giant hornet is also known as the Japanese giant hornet and the Murder Hornet. They're native to Asia, ranging from Japan and Russia down to Thailand and Myanmar (formerly Burma). But they were first discovered in the US in the fall of 2019 in Washington State. At that time, only two Murder Hornets were discovered, but since then, two new, unconfirmed sightings were reported in April of 2020. These hornets most likely arrived to the US as unseen stowaways in packing crates.

Top Facts About Asian Giant Hornets

• Asian giant hornets can reach 2 inches in length
• Their wingspan reaches more than 3 inches long
• Only females have stingers, which can reach .2 inches in length
• Their stings deliver a potent neurotoxin, which is nearly seven times the amount of venom that a honey bee delivers
• Asian giant hornets are able to sting repeatedly
• Nearly 50 people a year die in Japan from Murder Hornet stings, mostly due to allergic reactions
• However, multiple stings can kill humans, even if not allergic

Murder Hornets Attacking Honey Bees

Murder hornets are a significant predator to the European honey bee. The biggest fear from these hornets is the damage they do to honey bees, which are responsible for most of the pollination of crops across the US. Honey bees contribute an estimated $15 billion each year to the U.S. economy through their pollination services, far more than any other managed bee, according to the Scientific American.

Hornets are most destructive in the late summer and early fall, when they're on the hunt for sources of protein to raise next year’s queens. This is when the Asian giant hornets will attack honey bee hives. Attacks on beehives come in three phases...

1. First, the hornets hunt individual bees from a hive that has been chemically marked by another hornet. Once captured, the hornets rip the bees to pieces and carry the dismembered bits back to their hive and feed it to their own larvae.
2. Next is the slaughter stage, where dozens of hornets attack the hive and massacre tens of thousands of bees. "Within a few hours, a strong, healthy, and populous honeybee colony of 30,000-50,000 workers is slaughtered by a group of 15 to 30 hornets," according to a Washington State University report.
3. In the final phase, the hornets move into the defeated hive and feed on the abandoned larvae and pupae, making it into a “bee paste” and take it back to their hive and feed it to their own young.  The hornets are very aggressive during this stage and may attack animals or humans that wander too close to the occupied beehive.

The Murder Hornet was originally sighted near Blaine, WA and on Victoria Island in Vancouver, BC. No hornet hives have been discovered, but spring is the mating season, so there are numerous warnings posted in Washington.  

To read more about the Murder Hornet, check out the WSU Fact Sheet.