Some experts cited in Xinhua stated additional factors such as increased vegetation and a decrease in the hornets' enemies, such as spiders and birds, because of ecological changes.
In other words, it's a good season for the hornet population, which makes it a bad season for people who encounter them.
The provincial government of Shaanxi has warned residents to wear long sleeves when outdoors and not to attempt to drive the swarms away or remove the hives.
Japan is familiar with Asian giant hornet stings, too. About 30 to 50 deaths are reported each year in Japan from such attacks, according to Japanese studies. Most of the deaths are due to allergies to the venom, Makino said.
The giant hornets are also destructive to western honeybees. Research in Japan suggests that tens of thousands of honeybee hives are damaged by the giant hornets each year.
How to protect yourself
People run into trouble when these hornets form a nest: a basketball-shaped nest that looks like it's made of gray paper, sometimes under an eave, Schmidt said. If you disturb one of these, or happen to whack a tree that has a nest in it, the hornets may respond as if they're under attack.
Humans can get themselves in danger by reacting poorly to these large hornets. If you see a nest or a hive, just avoid it, Schmidt says. If one of them buzzes around you, don't panic.
"Don't flap or scream or freak out," he advised. "Just calmly walk away."
One victim told local media this month that "the more you run, the more they want to chase you." Some victims described being chased about 200 meters (656 feet) by a swarm.
An area of research that hasn't been explored is how many people get stung by these hornets while taking down a nest in order to use the larvae as fish bait, or even to eat. The larvae do not have venom, Schmidt explained. But in general, people should not tamper with these nests.
As powerful as their sting can be, it is highly unlikely that these hornets would travel all the way to the United States to find a new home, Schmidt said, or in the United Kingdom for that matter. To go to Western Europe, they'd have to cross some "nasty deserts" to which they are not adapted.
As deadly as live adult giant hornets can be, some people don't shy away from them altogether.
There is a sports drink in Japan called VAAM that incorporates amino acids derived from hornets.
In Taiwan, where the giant hornet is known as the "tiger head," the insect is sometimes used in alcoholic drinks, Starr said, the idea being that "the essence of this great big strong hornet will go out into the booze, and when you drink it, you'll become strong."
That's one way to get a buzz.