Pokhara, 28 January | A recent scientific investigation conducted by the Forest Research and Training Centre has confirmed that the widespread browning and denudation of Sal forests in Dang, Dailekh, and Surkhet districts are caused by a ‘defoliator’ insect outbreak, not forest fires. After local stakeholders and media reported a fire-like appearance in the woods during the spring season, a three-member expert team led by Under Secretary Sunita Ulak conducted field visits to the affected areas. The team, which included Professor Dr. Prem Budha from Tribhuvan University, found that hairy larvae belonging to the Erebidae and Lasiocampidae families had consumed Sal leaves at an alarming rate, leaving the forests looking barren and desolate.
The study covered approximately 193 hectares of forest land where Sal trees were completely stripped of their foliage, while adjacent pine trees remained untouched, indicating that the pest is host-specific to the Sal species. Experts have identified the larvae stage, commonly known as caterpillars, as the primary culprit for the destruction. Professor Budha noted that while there are hundreds of insect species associated with Sal, only a few reach epidemic levels. A significant contributing factor to this year’s outbreak was the prolonged winter drought and rising temperatures, which provided an ideal breeding environment for the insects. Observations revealed that forests facing south and west were more severely impacted. The local communities reported that the lack of Sal leaves even hindered cultural traditions, as they could not find leaves to make traditional plates (Duna-Tapari) for festivals and weddings.
To mitigate further damage and prevent future outbreaks, the expert team has proposed several technical interventions. Since these insects are expected to become active again in February and March as temperatures rise, the use of ‘light traps’ to capture adult moths has been recommended to local forest offices. Additionally, pruning branches and cleaning forest floors during August and September could significantly reduce the insect population for the next cycle. The research also suggested experimenting with controlled burning in specific patches to destroy larvae hidden in the soil. Moving forward, the centre plans to conduct another field visit in the coming months to precisely identify the moth species through lab culture and develop a long-term management strategy. Community forest user groups have been urged to report initial symptoms immediately to ensure timely technical support and prevent the recurrence of such ecological disasters.
