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 October 16, 2013
Killer hornets wreak havoc

 Red alerts after rapid increase in number of venomous insects poses huge threat to people's safety, He Na reports.

If you ask what are the most-feared venomous animals and insects, most people would say snakes, scorpions and spiders. But if you ask that question in the villages around Ankang in Shaanxi province, the answer is universally, "hornets".

The villagers live in mortal fear of hornet attacks and will happily take a long detour home rather than face the prospect of encountering the insects en route

Tales of people attacked by hornets can be heard almost everywhere in the southern part of Shaanxi. Farmers have been attacked while working in the fields, while walking home, by touching a tree that houses a hornets' nest, being stung when attempting to move nests, or being chased by hornets because of the color of their clothing ... the list goes on and on.

The experiences may vary slightly, but the result is always the same: severe injury or death.

Cheng Conghui, 55, a farmer from Sanping, a village in Ankang, was recently attacked as she walked through a rice field. Although she had taken the precaution of wearing a long dress and trousers, her caution proved fruitless when she encountered a large swarm of hornets, according to reports in Shaanxi Daily.

The doctor who treated Cheng at the local hospital estimated that she had been stung more than 200 times from head to toe and said that very few places on her body were free of the livid red marks.

Another victim, Chen Changlin, who was attacked on Sept 21, is still being treated at Ankang Central Hospital, having been diagnosed with acute renal failure as a result of the venomous stings.

He was attacked when he attempted to help a mother and son who were encircled by hornets. Chen, who was helping a relative to harvest rice, rushed to help, a move that aggravated the hornets, which launched a concerted fierce three-minute attack.

"The hornets chased him more than 200 meters. Hemodialysis is the only treatment for his condition, but we don't yet know how much money we will need to pay for his treatment," said Chen's son.

Even so, these two were lucky compared with those who have died as a result of hornet attacks. People's Daily reported that on Oct 3 an elderly woman in Luoping village, Ankang, died after being attacked as she tried to protect her 4-year-old granddaughter.

The 72-year-old died while being transferred from a clinic in the town to a large hospital. Her granddaughter is still receiving treatment in hospital and is on the "life at risk" list.

Reports by China National Radio show that so far, more than 1,600 people in the Shaanxi cities of Ankang, Hanzhong and Shangluo have been attacked by hornets since July. The death toll currently stands at 42. The National Health and Family Planning Commission has dispatched three medical experts to the province to provide guidance and assistance with the most severe cases.

Small, but deadly

Li Tiesheng, an insect researcher at the Chinese Academy of Sciences' Institute of Zoology, who has visited Ankang on several occasions, said that in recent times, the hornets responsible for the most severe attacks were mainly Vespa Mocsaryana and Vespa Mandarinia, often called the Asian giant hornet. Their nests, the diameter of which can reach 40 or 50 centimeters, can house between several hundred to 10,000 hornets. They are often located high in trees and look like giant gourds. As a result, the locals often refer to the insects as "gourd hornets".

An adult hornet is roughly the size of a human adult's thumb. In addition to their impressive size, they are easily irritated, nervous, have a fierce character and are highly aggressive.

"Any people or animals touching the nest, whether on purpose or not, are vulnerable to group attacks. The yellow and black insects will use their stings, which are roughly 6 millimeters long, to inject a poison so powerful that it can dissolve human tissue," said Li Tiesheng.

While minor injury can cause breathlessness, a rapid heartbeat and violent trembling, serious attacks often result in death from renal failure or anaphylactic shock.

Li Tiesheng attributed the rising number of attacks to global warming in part. "The rise in temperatures has resulted in a greater number of hornets surviving the winter months, leading to a corresponding rise in overall numbers in recent years. Besides, this is the hornet's reproduction period. Like other creatures with high levels of aggression and vigilance in the reproduction period, they will carry out crazed attacks to protect their pupae," he said.

The attacks have mostly occurred in the southern part of Shannxi, mainly as a result of the rich diversity of plant species in the local Qinling Mountains and improvements in the local environment that provide sufficient food for the hornets' survival, he added.

Li Xin, a professor of insect research at Northwest Agricultural and Forestry University, concurred with Li Tiesheng's view that the wide range of plant species and environmental improvements have provided the hornets with a greater choice of sites to build their nests and proliferate.

"The market prices of some woodland produce such as fruit, medical herbs and hornets' nests are much higher than usual. The high profit margin drives more people to the mountains to pick fruit and collect herbs, but this activity disturbs the hornets. Generally they don't attack people. The safe distance to keep from a hornet is two meters, but once people enter their scope they will quickly attack because they feel threatened," he said.

He pointed out that although the hornets are color-blind, they have a keen sense of smell and are intrigued by moving targets. However, if one wears dark clothing, preferably brown, and does not move, the insects can't see you. "But a lot of people don't know that. They wear bright-colored clothing and run quickly when the hornets chase them. To the hornets, this is deliberately provocative behavior which prompts them to attack," he said.

According to Li Tiesheng's research, 36 people in the city died from hornet stings from 2002 to 2005. There are some 12,000 hornets' nests scattered across Pingli county, while the human population numbers 220,000.

The rapid increase in the number of hornets has become a huge threat to the safety and property of local people, and the task of killing hornets is at the top of the agenda in some areas.

In addition to local government warnings posted online and pasted to walls and roadside trees, a number of methods have been employed by local fire brigades and villagers to destroy the hornets' nests, including the use of fire, water and gasoline.

However, while local governments have spared no efforts to deal with the hornets, the results have been less successful than anticipated. Li Tiesheng blamed the relative lack of success on inappropriate methods, which fail to take the hornets' habits and lifestyles into account.

"They are easy to deal with if you know their habits and character well," he said.

"When the temperature falls below eight degrees Celsius, adult hornets will abandon the nest to find shelter from the winds during the long winter. Generally, 1,000 to 2,000 will swarm together in the corners of buildings, such as those used to house pigs. The hornets don't move or eat during the winter, they just sleep. The villagers should search out these gathering places during the winter and use pesticides to kill the hornets. That would be an effective way of reducing their numbers.

"Hornets begin building their nests in winter. Each hornet builds its own nest, which increases in size as the offspring develop. It's easy to destroy the nests if fewer hornets are inside," he said.

He also stated that hornets are night blind and therefore the hours of darkness, especially rainy nights, are the best times to fight them.

Yang Guanhuang, a researcher at the Bee Research Institute of the Chinese Academy of Agricultural Sciences, advised covering the nests with red cloth bags late at night. Once the insects are safely contained in the bag, it's easy to use water or pesticides to kill them.

The bureau's research suggests that one hornet can eat 1,000 flies and 1,000 other pests over the course of their yearlong lives. Therefore one nest can protect approximately 333 hectares from pests.





Li Tiesheng noted that several provinces have introduced hornets in cotton fields to kill pests. The results were encouraging.

"The adults, larvae and the nests all have a high medicinal value. Extracts from the poison can be useful in the treatment of arthritis and can kill cancer cells for a short time, until they become immune," he said.

According to Li Xin: "Hornets eat flesh, especially pests. But they also love sweet-tasting things, so they are very destructive to fruit crops. It's hard to define whether hornets are good or bad. However, as a crucial link in the food chain, from the point of view of maintaining the ecological balance, we should remove hornet nests that disrupt our lives, such as those in villages, but keep the others and attempt to coexist peacefully."

Ecological imbalance

Yang Guanhuang said human are partly responsible for the plague of hornets. It's the result of the ecological imbalance and a sharp decline in the number of Chinese honeybees.

As part of an economy drive in the 1970s, farmers stopped breeding indigenous Chinese honeybees, preferring to breed the Western Honeybee, Apis Mellifera, which produces a higher volume of honey.

The increase in the number of these bees has resulted in the domestic variety being pushed to the edge of extinction.

Because farmers are concerned with higher honey yields, they often fail to pay attention to the negative aspects associated with European bees. While Chinese bees will pollinate every variety of flower they encounter, the European bees only favor large groups of plants that are rich in the sources of honey.

Without Chinese bees, many plants, especially rare flora, remain unpollinated. As more plants wither and become extinct, the numbers and varieties of pests have declined, which in turn has led directly to the birds abandoning farmland. Because birds are the hornets natural predators, their departure has resulted in a rise in the number of hornets. Increasing the numbers of Chinese honeybees would be a fundamental way of resolving the hornet problem, he added.

"The plague of hornets is just a small lesson that nature has taught us. Without the Chinese bees, our special mountain plant species will die out and that will affect every species in the food chain, including human beings. That's not hyperbole, it's just the truth".