Huge swarms of locusts are ravaging grasslands and farmlands in many parts of China amid the lingering summer heat, and local authorities have resorted to aerial spraying of pesticides to kill the insects.

Authorities in northern Inner Mongolia Autonomous Region have monitored locusts which have infested 3.9 million hectares, or 4.5 percent of the region's total area of grasslands, according to the latest figure released by the Department of Agriculture and Animal Husbandry (DAAH) of Inner Mongolia.

The hot and dry weather were believed to have triggered the ravaging by the insects, which are harmful to crops and grassland, said Zhang Zhuoran, chief of the vegetation conservation section of the DAAH.

Adding to the problems, the temperature in the region has been three to five degrees Celsius higher than the average during the same period since June, and the precipitation during this period has been 50-90 percent lower than usual in most of the region, Zhang said.

The DAAH has mobilized more than 6,000 people and five planes for locust control, completing nearly 130,000 hectares of pesticide spraying.

Additionally, local herdsmen and government have been participating to clear the spraying area beforehand to ensure no human beings or livestock would be affected by the harmful pesticides, he added.

A similar situation has occurred in China's Hainan Province, Shandong Province and Xinjiang Uygur Autonomous Region.

Nearly 9,000 hectares of crops are suffering from the locust plague, with a density of 20 insects per square meter in China's southern-most Hainan Province, said Zhang Chundong of the provincial plant protection department.

If the situation worsened, it would harm the sugar cane and rice harvests, which are major crops grown in the province, said Zhang.

Abnormal weather this year has increased the uncertainty of the plague, as the air temperature and moisture in the soil are key factors for the insects' existence and growth, said Mu Chen of the grasshoppers and prairie rats control headquarters in Xinjiang, where herdsmen have built nests to attract locusts' natural enemies, the birds.

In east China's Shandong Province, matrine and other bacterial parasites of locusts are used as biological pesticides, which are harmless to the environment and other creatures.

Further, two planes sprayed crops from June 18 to July 3 on 52,000 hectares, nearly 20 percent of the total locust-infected area, according to the locust control headquarters of Shandong Agricultural Department.