Sal forests in Madhya Pradesh face ‘alarming’ die-off as borer infestation spreads

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 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.

Now, 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 Down To Earth 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.

Local media reports cited forest officials estimating only 5,000 affected trees in Dindori. But this figure appears unreliable. Observations during Down To Earth’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. A scientist from the Tropical Forest Research Institute in Jabalpur, who recently visited Karanjia, described the situation as “alarming”. He said around 30-35 per cent of sal trees had been affected by the pest.

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 Down To Earth 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. C Mohan, a scientist at the Tropical Forest Research Institute, explained that a female sal borer can lay up to 250 eggs a day, underlining the insect’s capacity for rapid expansion. “The pest has the potential to devastate an entire forest,” he warned. 

With the larvae concealed inside tree trunks, it is impossible to determine their numbers at present. Climatic factors driving their proliferation this year, he added, urgently require study.

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.