Moth outbreak kills Siberian forests, turning them into wildfire fuel

Siberia's forests are burning, transformed into a tinderbox by an insect outbreak that has killed trees across vast regions. The culprit is the Siberian silk moth (Dendrolimus sibiricus), whose caterpillars have stripped needles from fir, spruce, larch, and pine trees over recent years. In the cold, dry climate, these dead trees stand upright and do not decompose, creating a highly flammable landscape.

This year, unusually hot and dry summer conditions have ignited these dead forests, leading to wildfires spreading beyond human control. The Siberian silk moth outbreaks are a recurring phenomenon, typically occurring every ten to eleven years and lasting for two to three seasons. A single outbreak can devastate hundreds of thousands of hectares.

Research into the moth's life cycle reveals complex factors influencing its population dynamics, with distinct molecular signatures suggesting a more intricate mechanism than just temperature or food availability. While a conifer can usually survive losing its needles once, consecutive years of defoliation prove fatal. This deadwood, now fueling the current fires in Krasnoyarsk, was likely a result of an outbreak that peaked years prior to this fire season.