Intensifying drought and above-average temperatures allowed native bark beetles to run rampant in New Mexico’s forests in 2025, resulting in a tripling of tree mortality over 2024, according to a new report from the New Mexico State Forestry division.

The report, based on aerial assessments of more than 14 million acres of forest on tribal, state, federal and private lands, found that bark beetles killed more than 200,000 acres of trees, predominately in the Gila National Forest and Sacramento Mountains, last year. In 2024, bark beetles killed 67,000 acres of trees.

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Most of the tree deaths in 2025 — roughly 123,000 acres — occurred among ponderosa pines in the Gila National Forest, according to the report. Victor Lucero, the New Mexico Forestry Division forest health program manager, told Source New Mexico on Monday that the drought and high temperatures in the region left swathes of forestland vulnerable to bark beetle attacks.

Drought deprives trees of their main defense: sustained sap flow, Lucero said. Meanwhile, prolonged high temperatures mean multiple generations of bark beetles can spawn within a season. The beetles feed on the vascular tissue of trees, depriving them of the ability to replenish carbohydrates and killing them as a result.

“And so you have an exponential growth of population and, as a result, you have greater probability of not just a clump of trees, but an entire landscape that is experiencing those dry, warm conditions to experience attacks,” Lucero said.

Native bark beetles are usually a boon to forests, targeting vulnerable trees and helping to thin dense stands of trees and allow new growth. But the hot temperatures have upset that balance, leaving whole swathes of forest vulnerable to attack, Lucero said.

While he described the tripling of tree deaths as “staggering,” Lucero noted that bark beetles have killed far more trees in previous years. In 2013, for example, beetles killed more than 220,000 acres of ponderosa pines.

The study also found a major reduction in trees losing their leaves due to pests in 2025. Statewide, “defoliation” decreased by about 168,000 acres from last year’s total of 327,000 acres.

Lucero said he was still unsure what exactly caused the decrease, though the report notes that the main culprit in defoliation — the Western source budworm caterpillar — was far less active in 2025, defoliating 34,000 acres of land, mostly in the Santa Fe and Carson national forests, compared to 119,000 in 2024.

Overall, the state experienced its second-warmest year on record last year, and conditions so far in 2026, exacerbated by record-low snowpack, are not promising, Lucero said.

“Since we didn’t have much of a winter, we started seeing [bark beetle] activity this year,” he said, “well before what would be normal activity, because it was so warm and dry.”