Oct 5 2013




National Geographic is reporting that in Northwest China the world's largest hornets have killed 42 and injured 1,600 in vicious attacks. The Asian Giant Hornet attacks began in July. The hornet is huge (about the size of a thumb) and deadly.

Here is an excerpt from the magazine.

The problem with this particular hornet is that it's big, sort of thumb-sized, and it packs a lot of venom," said entomologist Lynn Kimsey, director of the Bohart Museum of Entomology at the University of California, Davis.

"And its nests get fairly large, including maybe several hundred individuals. They are aggressive, they are predatory, and they have been known to kill and eat an entire colony of honeybees," she said.

At 1.5 to 2 inches (4 to 5 centimeters) long, the giant hornets are found across many parts of East and Southeast Asia and are especially well known in Japan. They're among the more dangerous venomous insects of their type, Kimsey said, though others, like Africanized bees and yellow jackets, can cause similar problems.

Bee-Loving Hornets

While the hornets don't typically swarm humans in such numbers, they're well known for their ability to quickly decimate a hive of thousands of honeybees, leaving behind a trail of severed heads and limbs.

The hornets routinely fly miles from their nests and employ scouts to locate a bee colony and then mark it with a special pheromone that attracts their allies to attack, destroy, and occupy the hive.

With their huge size advantage, the hornets typically make short work of the bees, unless the victims are able to eliminate the advance scout before it can summon others. They sometimes do so with an incredible defense—swarming the hornet in a ball and literally cooking it to death.

Often, however, the bees and other insect victims become fodder for the growth of the hornet hive. Adult workers chew their victims' flesh into a nutritious paste that feeds larvae, which in turn produces saliva that serves as a powerful "energy drink" to be consumed by adults who cannot digest solid protein.

Why Are Hornets Attacking People?

It's unclear exactly what factor or factors has led to the hornets' deadly season of human attacks.

Huang Rongyao, an insect expert with the Forestry Bureau of Ankang City, told Xinhua that local vegetation growth has increased hornet habitat, and that two months of hot weather have made the insects much more active. Ankang is one of the cities most affected by hornet attacks, along with Hanzhong and Shangluo.

Hua Baozhen, an entomologist at China's Northwest Agriculture and Forestry University, pinpointed a decrease in populations of the insect's natural enemies like spiders and birds, while other experts speculate that urban sprawl simply means more people are living in what was formerly hornet country.

Kimsey noted that this type of behavior is often seen with invasive species, though she's not sure if the hornet is native to the region or how long it may have been there.

"What we see happen when you get a newly introduced species is that it may sort of go along relatively unnoticed for years, but then eventually you see a huge outbreak. We have that happening in California, where the European paper wasp was introduced 20 years ago, and now suddenly it's an outbreak and they are everywhere."