Sal forests in Madhya Pradesh face ‘alarming’ die-off to borer infestation; 100,000 trees may be at risk

It is four in the afternoon in Sontirath village, in Madhya Pradesh’s Dindori district. The village forest is bustling with activity. Suddenly, the sound of axes echoes through the trees. For a moment, it appears that trees are being felled illegally. But, on approaching and questioning the workers, it becomes clear that they are labourers marking sal trees.

One of them, Sukal, aged 70, spoke in a despairing voice. “The entire forest is crying. The forest is drying up rapidly. This year, the sal borer pest has caused significant damage,” he said. For the past four to five years, he explains, the borer’s impact had been mild. This year, however, the damage is so severe that workers have been instructed to mark the affected trees. Marked trees can be felled.

This is not the first major outbreak of the sal heartwood borer in Madhya Pradesh. Previously, in 1995, an infestation spiraled into an ecological disaster, Down To Earth (DTE) had reported. Although the pest is endemic and manageable, early warnings were ignored for years, with locals alleging the outbreak's beginning dated as far back as 1992.

When the infestation exploded, their only solution was mass felling of sal trees, leading to the cutting of over half a million trees, including many healthy ones. The outbreak infected more than 200,000 sal (Shorea robusta) trees and caused losses worth Rs 1,200 crore in Madhya Pradesh alone, was the worst sal borer epidemic the country had seen in more than 100 years.

In 2015, DTE reported that cases of sal borer infestations were steadily increasing in Madhya Pradesh’s Mandla and Sidhi divisions. Sal forests account for 25 per cent of the forests in India. While stray borer infestations are common, scientists say forest departments should closely monitor the population because a major onslaught is registered in the country every 20 years.

This time, around 35 labourers have been marking trees damaged by the sal borer pest in Sontirath for the past four days. The forest, located in Coup No. 776, covers a 119.25-hectare sal-dominated area. So far, just three hectares have been marked, with 3,113 affected trees counted. Workers said that marking the entire 119.25 hectares could take a month, and estimate that the number of damaged trees in Sontirath village may reach 100,000. The figures for the entire district are expected to be staggering.

Forest department officials are reluctant to speak publicly. They said they are awaiting instructions from senior authorities. Karanjia Ranger Kaushambi Jha told DTE that she was not authorised to comment. She said a team of scientists had visited the area and prepared a report, which she had yet to receive.

The divisional forest officer of Dindori, Puneet Sonkar, told DTE that a report of the areas visited by the team of scientists is awaited. “We are currently estimating the number of trees affected by the pests,” said Sonkar, while admitting that the impact is greater this year compared to the last few years.

Local media reports cited forest officials estimating only 5,000 affected trees in Dindori. But this figure appears unreliable. Observations during DTE’s field visit in Sontirath indicate a far higher number of damaged trees, and villagers also believe the official figure significantly underestimates the scale of the problem. According to forest officials, scientists have warned that around 30-35 per cent of sal trees have been affected by the pests in their study area. This figure could be as high as 50 per cent in some of the worst-affected areas, according to local residents.

Villagers in Chauraddar, another settlement in Dindori, report that many sal trees have dried up this year. Bharat Padwar, a resident of the village of 4,000 people, says that around 95 per cent of local trees are sal. If the infestation continues, he warned, “the entire sal forest will be wiped out in the next four to five years”. He recalled that the village was once cool, with no need for fans or coolers. Now, as the sal canopy disappears, temperatures feel noticeably higher.

Scientists believe the main driver of this year’s surge in borer numbers could be increased humidity following heavy rainfall. Locals and experts report heavy rainfall in the region for monsoon 2025. 

Dindori’s sal forests border Amarkantak in Anuppur district, where infestations have also been recorded. Amarkantak Ranger Virendra Kumar Srivastava told DTE that their initial survey found 6 per cent of trees affected. The 8,525-hectare forest in the region contains an estimated four million sal trees. The first assessment was carried out using one-hectare sample plots across all 47 forest compartments. A follow-up survey involving five plots per compartment was recently completed to gain a clearer picture of the spread.

Sal borers are currently in the larval stage and will remain dormant throughout winter. As soon as summer begins, they will emerge and start spreading. Research shows that a female sal borer can lay up to 250 eggs in its entire life cycle, underlining the insect’s capacity for rapid expansion. The pest has the potential to devastate an entire forest, according to researchers. 

With the larvae concealed inside tree trunks, it is impossible to determine their numbers at present. According to experts DTE spoke to, sal borer proliferates more because of increased rainfall and moisture. Given that that there have been good rains during and after the monsoon this year, both these conditions are prevalent. Climatic factors driving their proliferation this year urgently require study, according to experts.

The sal borer’s life cycle is closely tied to the monsoon, DTE reported back in 1998. Adult beetles emerge with the rains, with females laying around 250 eggs in the bark. The larvae hatch within a week and remain active for six to seven months, boring deep into the sapwood and heartwood and creating extensive tunnels inside the trunk. They pupate within the tree and re-emerge the following monsoon.

Adult borers are strongly attracted to fresh sap — able to detect it from up to 2 kilometres away — and can reach newly felled trees within minutes.

The sal tree does attempt to defend itself by exuding resin, drowning up to 85–100 per cent of larvae when attacks are limited. But this response weakens the tree, and in years of heavy infestation it cannot produce enough resin to cope, resulting in the characteristic yellow trickles seen in affected forests.

The forest department introduced the trap-tree method in 2000, which is the only effective way to control sal borers. It involves felling a healthy sal tree (60-90 cm girth), cutting it into logs and beating the ends to release sap that attracts the beetles.

Once the borers settle on the logs after feeding, workers inspect them twice daily and decapitate the trapped insects for counting. Typically, one or two trap trees are used per hectare, and operations begin with the first monsoon showers and continue until no beetles are caught for three consecutive days.