NM Forestry Division: Bark beetle tree mortality more than doubled for second consecutive year

Though the focus of his expertise is firmly rooted underground, Victor Lucero spends many hours each year working for the New Mexico Forestry Division from the air.

Every week from mid to late June through early September, the division's forest health program manager boards a small single-prop Cessna to scan millions of acres of New Mexico's forests from a bird's-eye view. His goal, and that of the forestry colleagues who get airborne alongside him, is to capture a snapshot of the overall health of the state's forests.

What he's seen in recent years troubles him.

For the last two years in a row, many more of the trees Lucero has observed from his porthole airplane window have become discolored as a result of defoliation and desiccation, driven primarily by two native insects whose seasons are lengthening as winters grow warmer in the state: the Douglas fir tussock moth caterpillar and the piñon ips bark beetle.

At higher elevations, tussock moth caterpillars continue to weaken and in many cases kill conifers by defoliating their pine needles, though overall damage by this insect decreased last year. The more damaging of these two tiny offenders, Lucero said, is the bark beetle, which mainly targets piñons, the state tree, which become compromised by ongoing drought fueled by exceptionally warm, dry winters.

"This insect begins its active biological cycle when the daily average temperature is around 55 degrees Fahrenheit," Lucero told the Journal. "And we saw those temperatures well into the end of September and even parts of November in different areas of the state, especially in the southern reaches and the middle portions of New Mexico, near Datil, the Lincoln area and the Gila region, as well as some parts of the east mountains, where we're seeing (bark beetle) activity later than usual."

Lucero believes the unseasonably warm winters New Mexico has seen over the last two years has driven dramatic increases in insect-caused tree death observed statewide.

According to his annual survey, 209,000 acres of trees died in New Mexico as a result of bark beetle activity in 2025 — well over double the 67,000 acres recorded in 2024. Drought impacted trees in the state rose from 7,000 to 12,000 over the same period, and tree mortality also doubled from 2023 to 2024, according to the survey.

Record high temperatures were recorded in parts of New Mexico last month as the state experiences its second year of a La Niña climate pattern, which originates in the tropical waters of the Pacific Ocean and generally results in higher average temperatures and less precipitation in the southern U.S. during winter while the opposite is seen in northern states.

David Gutzler, professor emeritus of climatology and meteorology at the University of New Mexico, said the heat the state has seen again so far this winter is unusual, even for the relatively arid Southwest. Still, those conditions are expected to persist in spite of a cold front headed for the state this week.

"I think it would be a mistake to try to portray what we've been experiencing for the last month or six weeks as anything that we should expect every year," he said. "It's very unusual, but on a shorter time scale, the forecasts we're looking at through the spring  don't include much relief for us."

In the fall, while flying over the Lincoln and Gila national forests in southern New Mexico, Lucero said he saw firsthand the impacts of the general warming pattern New Mexico has seen in recent years. Enormous swaths of trees have turned from a natural, verdant green to a desaturated red or brown due to vigorous insect activity amid higher temperatures.

"In the Gila region, we did see large areas of mortality due to bark beetle attack," Lucero said, noting that the current aerial survey period does not include the latest part of fall and early winter. "And that event continued on into the very late weeks of October, and possibly even into November based on ground checking, where we were actually going out and sampling trees on the ground."

The majority of tree mortality was observed on Forest Service lands, as opposed to the private lands the Forestry Division manages on behalf of the state. Forest Service personnel are among those who accompany him on many of his survey flights, Lucero said.

Through its work with private landowners across New Mexico, Lucero and his Forestry Division colleagues have been working to educate New Mexicans about how to protect trees on their property through thinning work and irrigation  — two of the only two tools that can effectively ward off bark beetles, which burrow deep into and consume conifer vascular tissue as they struggle to survive and reproduce.

"Thinning the density of trees in a particular stand, or what we call overstocked conditions of trees, allows the trees to gain access to soil moisture, which prevents them becoming stressed and attracting bark beetles," Lucero said.

Tree thinning is also a priority mitigation strategy for another rising danger for forests: wildfire, whose season has also been extending in the Western U.S. as a result of warmer, drier temperatures in recent decades, according to the U.S. Environmental Protection Agency.

"The timeframe for thinning would be during the coldest times of the year," Lucero said. "Typically that's November through March, but we're seeing that time window closing in on both ends of the time frame."

John Miller is the Albuquerque Journal’s northern New Mexico correspondent. He can be reached at jmiller@abqjournal.com.