Some 150 hectares (370 acres) of coconut groves in Ben Tre Province have been damaged by a caterpillar species endemic to India and Sri Lanka. 

In mid-March trunks of dead coconut trees could be seen scattered along either side of National Highway 60 in Chau Thanh District in Ben Tre, dubbed the coconut capital of Vietnam. With 74,000 hectares (182,800 acres), it accounts for half the country's coconut farming area.

In many groves, trees stand with withered tops, leaves gray and ragged.

An official in Huu Dinh Commune of Chau Thanh Disrict sits in coconut garden
where most trees have been chopped down due to black-head caterpillar invasion,
March 2021. Photo by VnExpress/Hoang Nam.

Pushing a cart into his grove in Huu Dinh Commune that had been over 40 years old, Vu Ngoc Hue picks pieces left from the trees that have been chopped down to use as firewood.

In July last year leaves and buds started drying up in a neighbor's grove. At first the owner thought the trees were affected by coconut bugs and simply sprayed pesticides. But it did not work, and the disease quickly spread to the entire garden within a month and then to Hue and other farmers' groves.

As locals have found out, it takes around two weeks for a tree to be completely destroyed from the time symptoms are first detected.

Hue has lost 5,000 square meters of coconut trees to the caterpillar.

Pointing to the top of a sick tree, Hue said that when a coconut tree is sick or old and does not produce good fruits, farmers chop it down to get the cu hu from inside the trunk at the top. In southern Vietnam, it is a specialty used in salads.

But the black-head caterpillar completely destroys treetops and there is no way to get the cu hu.

A black-head caterpillar at a coconut farm in Ben Tre Province, March 2021.
Photo by VnExpress/Hoang Nam.

Hue said: "Normally I earn VND1 million ($43) a month from selling coconuts. Chopping them down breaks my heart but I don't have any other choice."

Huynh Duong Thai, deputy chairman of Huu Dinh, said the commune has more than 760 hectares of coconut and 66 hectares have been damaged by the caterpillars, making it the worst affected locality in Ben Tre.

Farmers and researchers from some universities have tried both chemical and biological methods to destroy the pest, but so far nothing has worked.

Huynh Quang Duc, deputy director of the province Department of Agriculture and Rural Development, said the caterpillar, Opisina arenosella Walker, is a coconut pest originating in India and Sri Lanka, and has been reported in 16 countries.

A coconut fruit from a tree attacked by blackhead caterpillars in Ben Tre Province.
Photo by VnExpress/Hoang Nam.

In Ben Tre, it was first detected in Binh Dai District, and has within eight months spread to 150 hectares in five districts and Ben Tre Town, the capital.

The department has not been able to find out how the pest first intruded.

What makes this caterpillar more dangerous than others is that its larva stage lasts 40 days compared to just 10-14 days for other pests, and during this period it subsists exclusively on coconut fronds, thus completely destroying the tree.

The province has worked with experts to try and put an end to the pest.

Various methods have been explored in other countries, but an effective solution has evaded them, and destroying infected trees to prevent the caterpillar from spreading remains the only option.