So far, at least 1,200 tons of insecticide, 50,000 pesticide-spraying machines and four crop-dusting aircraft have been mobilized to control the insects.

Weapons being used against the locusts include a biological pesticide which experts say kills the insects but does not damage the environment.

Biological pesticides account for 10 percent of the total to be sprayed this year, Ministry of Agriculture official Zhu Enlin said yesterday.

Funds earmarked for the eradicating efforts total 12 million yuan (US$1.4 million), Zhu said, adding that “Migratory locusts are not occurring as massively as they did last year and may not pose great harm to crops.”

Action has been taken in nine northern provinces and municipalities including Shandong, Hebei, Henan and Tianjin, where estimates on Sunday put locust affected areas at 80 million hectares.

The density of locusts is five to 20 per square meter at present, compared with thousands per square meter last year, according to the Ministry of Agriculture statistics.

The comparatively light density this year is largely a result of last year's effective control measures, and heavier rainfall earlier this year, Zhu said.

Efforts to control the locusts are necessary to prevent the swarms continuing into the autumn, even though the current insect population is not itself a threat, Zhu added.

According to experts locusts' usual habitat is dry wasteland near rivers, lakes and reservoirs, but if their population density is too high they migrate to open land in search of food.

In an interview Monday, Lei Zhongren, a researcher with the Chinese Academy of Agricultural Sciences, said locusts, including migratory locusts and grasshoppers, cause losses of 60 to 100 million kilograms of grain each year.

To protect the environment and combat the locust population in a sustainable way, Lei said China has increasingly sought biological methods to control the insects.

A special fungus, metarizium-flavoviride, which is fatal to locusts, has been used in some infested areas in North China over the past few years.

Lei claims it has been effective in killing insects without damaging the over all food chain or the environment.

According to Lei, chemical pesticides can harm beneficial insects, birds and the environment. Because of this, China is to cut down on chemical pesticides and increase the use of biological pesticides in the future.

(China Daily June 28, 2005)