Terry Prouty An Asian giant hornet.

BEIJING – Authorities in northern China are struggling to control a spate of attacks by aggressive hornets that has now killed 42 people and injured at least 1,640.

Residents in the cities of Ankang, Hanzhong and Shangluo in Shaanxi province have been hardest hit, according to local news reports, with 206 people still in hospitals for treatment. Of those, 37 are said to be in critical condition.

The attacks are blamed on a particularly aggressive species of hornet known as the Asian giant hornet or Vespa mandarinia. At nearly two inches long (4.5 centimeters long) with a quarter-inch (6-millimeter) stinger, the Asian giant hornet is the largest in the world and has a reputation as a relentless hunter that stalks its prey — normally honeybees — in coordinated attacks.

The Chinese health ministry has ordered local authorities to exterminate the hornet hives in densely populated areas. Local officials have issued fire departments with special protective suits and pesticides and say that hundreds of hives have already been destroyed.

A team of medical experts from Shanghai has also been deployed to oversee and provide treatment to victims.

Health Minister Li Bin said in a statement Thursday that he was "paying close attention to the situation."

The unseasonably warm and dry weather in the region this fall — traditionally the normal breeding season for hornets — and continued human encroachment into hornet breeding grounds have been suggested as possible reasons for the recent rash of attacks.

Devon Henderson / Addicted2Hymenoptera via Flickr Asian giant hornet queens can exceed 2 inches (5.5 centimeters) in length.

Five times the size of a regular honey bee, one Asian giant hornet is capable of killing as many as 40 honeybees per minute. In humans, the venom released by this species of hornet is a potent neurotoxin that can cause violent allergic reactions and extreme bruising around the sting area.

State-run media have shown images of bedridden victims suffering from multiple stings that look like small stab wounds.

Shaanxi authorities have also urged citizens to wear long-sleeved clothing while outside and not to aggravate the hornets if they encounter them.

Related:

Series of deadly attacks by giant, vicious hornets terrorizing China

Correction for 8:35 p.m. ET Oct. 3: Due to a metric conversion error, the length of the hornet's stinger was overstated in an earlier version of this report.