Silkworm cocoons are being used to breed the insect, which attacks the pupa of the American white moth.
The State Forestry Administration says the moth is causing a threat in 116 counties of six provinces and municipalities. Some 300,000ha of plants have been eaten in Beijing, Tianjin, Hebei and Liaoning.
More than 50,000 trees have been attacked in Beijing, with moths reported to be still spreading in the city.
About 130,000 cocoons infested with the parasite have been put in a 260ha forest in the Yellow River Delta known to be affected by the moth. Beijing authorities hope to release about one billion parasites by the end of June.
