Beijing Releases Over A Billion Parasitic Wasps to Fight Invasive Caterpillars

Authorities in Beijing are releasing more than a billion parasitic wasps and encouraging caterpillar-catching competitions to contain the spread of the invasive North American fall webworm.

The response comes after the caterpillars blanketed trees in the Chinese capital and surrounding areas this summer.

Why the outbreak matters

The insects have spun clouds of greyish-white webs across trees as they eat through foliage. The caterpillars are the fuzzy larval stage of Hyphantria cunea, which later metamorphoses into adult white moths.

China Science Daily reported on Friday that the insects are not harmful to humans. However, they threaten hundreds of plant species, raising concerns about the damage their spread could cause to vegetation.

According to an article by Chen Min, a professor at Beijing Forestry University, this generation of larvae carries a greater risk of spreading than usual. Chen also said that the increased risk is making control measures more difficult.

The authorities’ plan therefore combines the release of parasitic wasps with efforts to remove the caterpillars directly through catching competitions. Both measures are being used as part of attempts to contain the invasive species after its wider presence across Beijing and surrounding areas.

The scale of the wasp release reflects the challenge posed by the outbreak, while the competitions add another method of dealing with the larvae as they continue feeding on tree foliage.

Source: South China Morning Post