AS she was watering her house plants and moving flower pots around, 26-year-old painter Xiao Nan found yet another a pile of dead insects on the shelf. It is the legacy of the termite swarms that erupted in Shanghai two weeks ago.

Great clouds of termites were seen flying around the old houses on Weihai Road at about 7pm on June 10. The termites swarmed around lights and thousands flew through open windows and doors into homes. Residents and shop keepers tried to repel them with pesticide spray or just squashed them with electric swatters.

At her studio at the 696 Space on Weihai Road, Xiao saw the termites suddenly invade her room while she was sweeping the floor.

"The insects suddenly came out of nowhere," recalls Xiao. "Not just a few but thousands of the tiny insects filled the room in no time."

Xiao's husband recognized that the insects were in fact termites and got out a vacuum cleaner.

"There were too many of them, we couldn't think of any other ways," says Xiao.

Their pet cat and the dog joined in helping to catch and kill the pests.

Almost all of her neighbors were invaded by the termites that night and the nightmare lasted three hours until about 10pm, Xiao says.

The same thing happened on June 3. David Zhou saw a large cloud of termites flying along Nanjing Road on his way home.

"It was just like a cloud in the air," says Zhou. "Many passers-by gathered around the cloud of insects just as I did, but nobody dared step nearer."

The recent occasional storms and high temperatures created ideal breeding conditions for termites, says Wei Yi, national technical and training manager of the Rentokil branch in Shanghai.

The peak reproductive season usually falls in June and July in Shanghai, yet the early arrival of summer this year seems to bring forward the termite swarms in Shanghai as well. The company was receiving calls for termite extermination as early as April this year.

Apart from Jing'an District, termites have also invaded other areas including Huangpu, Luwan, Xuhui and Changning districts since late May.

There are three kinds of termites - dampwood termites, drywood termites and subterranean termites, according to Wei. Just as their name suggests, dampwood termites live in damp wood, drywood termites live in dry wood and subterranean termites live undergound.

The territories of dampwood and drywood termites are usually limited to the wood they live in while the subterranean termites enjoy wider unlimited territory. They crawl out of the nest and search for food wherever it can be found. It is nicknamed "super-termite" because it's very destructive. Unfortunately, most of the termites in Shanghai are subterranean termites.

"Termites usually hide in damp and dim places and eat from inside out," says Wei. "If you see termites crawling or flying out of a piece of furniture or floorboards, I'm afraid that the furniture or floorboards have been chewed hollow already."

Zhuang Quan, an employee with Rentokil in Shanghai, says he has seen completely destroyed wooden boards and furniture when they look closely at some apartments.

As well as old houses with a lot of timber, termites are also found in modern downtown buildings mostly built with reinforced concrete. Though the termites don't eat concrete, some termites secrete formic acid which eats into the concrete making holes so they can move. Open windows are another invitation for a termite invasion.

Just like ants, termites have a caste system including a king, queen, workers, soldiers, and reproductives or alates (winged termites).

The workers provide food, soldiers defend the nest, and the reproductives breed the colony. The colony is led by a queen who has a life span of approximately 15 years and is capable of producing up to 2,000 eggs per day

"The alates should be killed at once before they land and start breeding in your house," says Wei. "Failing to repel or kill them in the first place will cause much trouble later."

If you find termites, close all the doors and windows, leaving only one light on in the room with a basin of water underneath it.

The termites will be attracted to the light and drown in the water. Or, you can simply kill them by spraying pesticide when they fly around the light.

And you can also discover whether the termites have just come from outside or are already nesting in your apartment. If termites fly in from other rooms in your apartment, you may need a professional exterminator to help you clear the nest.

"The termites you see crawling around may only be 5 percent of the total number in your apartment," says Wei. "As long as the queen keeps breeding, killing the visible workers won't help."

Fipronil is the main ingredient in the chemicals pest exterminators use today, she says.

Exterminators drill holes around the building and pump the chemical in. Worker termites will carry the chemical on them when they crawl through the holes. Carrying the chemical doesn't kill the termites immediately but ensures that it is taken to the nest. As termites help clean each other by licking, the chemical on their bodies will kill other termites in nest gradually including the king and queen.

Taking preventative measures such as spreading pesticides on the ground before laying foundations is better than killing or trying to control them afterward, Wei says. Preventative measures can help keep termites away for at least two to three years and even longer if the chemical barrier is not destroyed by alterations.

The Ministry of Construction released "The Administration of Prevention and Control of Termites in Urban Houses" in 1999 and amended it in 2004. The amended version says that a real estate development enterprise shall, when selling commodity houses or making advance sales, show the purchasers the "Contract on Prevention of Termites" or other documents on prevention of termites.

There are specific regulations in many provinces or cities, calling for termite preventative measures in new buildings, and the real estate development enterprise there shall pay the costs of termite control. But there are so far no such regulations in Shanghai.


Termites: Keeping the pest at bay

Hiring a professional team can help get rid of the termites in a house completely, but it is relatively expensive. The price of different termite-killing companies varies.

Usually, taking termite-prevention measures in commercial buildings under construction costs between three yuan (44 US cents) and four yuan per square meter; killing termites in a completed commercial buildings costs about 50 yuan per square meter; getting rid of a termite nest costs 2,000-4,000 yuan.

Taking termite-prevention measures in a building under construction is the most effective method. And it is advisable to call in a professional termite exterminator immediately if you see large number of termites at your home.

There are also some ways you can help before the professionals arrive.

1. Turn on a light and place a basin of water underneath it.

Flying termites will be attracted to the light. When they hit the lamp and fall, they will drown in the water beneath.

2. Seal the holes.

If you find holes where termites are flying or crawl in and out, seal them with plastic wraps. This will help stop more flying out to breed.

Some termite-prevention and control institutes' numbers:

Luwan District: 6305-0079

Putuo District: 5661-2619

Huangpu District: 6352-4756

Zhabei District: 6309-2609

Yangpu District: 6530-1621

Changning District: 1361-1919-987

The Subterranean termite (the Formosan subterranean termite): It is very destructive - it's called the super-termite.

It's usually found in large colonies and can destroy wood at an alarming rate.

A single colony may contain several million insects that forage up to 100 meters in the soil.

A mature colony can consume as much as 370 grams of wood a day and severely damage a structure in three months, posing serious threats to neighboring structures.

The Formosan subterranean termite acquires the name because it was first described in Taiwan in the early 1900s, but it is actually a native to south China, including Shanghai.

There were major termite swarms in the 1960s-1970s in Shanghai, with almost everybody participating in the extermination of the pests.