Beetle-kill trees make an easy target in the rush to defend our forests and communities from wildfire. The trees are dead and brown, so they must be a fire hazard, especially in today’s unnaturally dense forests. Therefore, we need to cut the trees and salvage valuable timber before it rots. That’s the basic reasoning behind wildfire-mitigation logging projects following native insect outbreaks on our national forests. These projects, along with other fire-mitigation projects, are receiving unprecedented levels of federal funding.
While the justification for logging beetle-kill trees may at first seem reasonable, questions arise when this presumed connection is scrutinized. It doesn’t take a scientist to notice that the most destructive U.S. fires in recent years did not start in stands of dead trees and were not fueled by dead trees. In fact, several of the worst fires were not fueled by trees at all — e.g., 2021, Boulder County, Colorado, grassfire; 2023, Lahaina, Hawai’i, brushfire; 2024, Texas Panhandle, grassfire; 2025, Los Angeles, California, brushfire.
Five researchers, including Dr. Garrett Meigs (Washington Department of Natural Resources) and Dr. Harold Zald (U.S. Forest Service) studied wildfire severity in the aftermath of mountain pine beetle and Western spruce budworm outbreaks across the Pacific Northwest. The researchers determined, “In contrast to common assumptions of positive [wildfire] feedbacks, we find that insects generally reduce the severity of subsequent wildfires…. Both insects decrease the abundance of live vegetation susceptible to wildfire at multiple time lags.” Meigs and his fellow researchers embarked on this large-scale research project after several smaller, localized studies reached similar conclusions.
For example, researchers led by Scott Black, executive director, Xerces Society for Invertebrate Conservation, reviewed the scientific literature on “fire risk following bark beetle outbreaks” in several Central Rocky Mountain forest types. Their findings, published in 2013, reveal, “Most available evidence indicates that bark beetle outbreaks do not substantially increase the risk of active crown fire in lodgepole pine and spruce-fir forests under most conditions.” Instead, crown fires in these forests “are primarily contingent on dry conditions.”
The 2013 study also indicates preemptive thinning “is unlikely to reduce susceptibility to large, landscape-scale [bark beetle] epidemics.” These forest treatments could also “have substantial, unintended short- and long-term ecological costs” — i.e., ecosystem degradation. The authors recommend concentrating fuel reduction measures on creating defensible space around homes and communities — “to be effective at reducing fire hazard to communities, tree-cutting can be directed at removing all flammable material in the immediate vicinity of homes and settlements.”
A 2014 paper by Diana Six, Eric Biber, and Elisabeth Long analyzed the issue from a policy perspective. Noting “a widespread belief in the policy arena that timber harvesting is an effective and necessary tool to address beetle infestations,” the authors point to “a dearth of monitoring to assess outcomes” and failure to report unsuccessful outcomes. In spite of these shortcomings, a belief in the effectiveness of logging has led to “significant changes in federal environmental laws to encourage more timber harvests for beetle control.”
Widespread acceptance of logging as a good response to bark beetle outbreaks (by policymakers) “raises a number of red flags.” One red flag identified in this analysis is the political motivation behind policies advancing logging activities — revenue for the commercial timber industry. Given the lack of post-logging monitoring and the absence of long-term studies, the authors suggest that beetle-kill logging projects are likely “producing more harm than good.” They conclude that policymakers need a better understanding of existing science and additional scientific data to support forest management that best ensures long-term ecosystem function “while wisely using limited financial resources.”
A study conducted by University of Colorado researchers in 2014 examines the effects of mountain pine beetle outbreaks on the extent of areas that burned in the West between 2002 and 2013. The study focused on peak wildfire years, which account for 46% of area burned during that 11-year span. “Contrary to the expectation of increased wildfire activity in recently infested red-stage stands,” the researchers “found no difference between observed area and expected area burned in red-stage or subsequent gray-stage stands.” The authors conclude, “Despite the widespread public perception that forests affected by recent mountain pine beetle outbreaks are more likely to burn, we find that the annual area burned across the western United States is unaffected by mountain pine beetle infestation.”
Meigs and Zald, prior to publishing their 2016 report, worked with an Oregon State University research team to compile 28 years of data on wildfires and 42 years of data on insect outbreaks (mountain pine beetle and Western spruce budworm) across approximately 100 million acres in Oregon and Washington. Their study, published in 2015, is one of the most comprehensive to date and addresses the limitations of previous computer-simulation studies and small-scale data-driven studies. They found “no clear associations between fire likelihood and fire size,” and their “central finding” is, “Wildfire likelihood does not consistently increase or decrease in areas affected by recent insect outbreaks;” in fact, “Western spruce budworm outbreaks are associated with decreased fire likelihood.”
These findings have important implications for forest management. For one, the decreased likelihood of wildfire associated with spruce budworm outbreaks suggests that these insects “function as forest thinning agents, potentially benefiting ecosystem restoration and fuel-reduction strategies.” Since both insects addressed by the study are native to Western forests, they “likely contribute to the pyrodiversity inherent to mixed-severity fire regimes,” making it unlikely that they represent a forest health crisis. “These findings suggest that strategic plans should recognize (1) the relative rarity of insect-fire interactions and (2) the potential ecosystem restoration benefits of native insect outbreaks, when they do occur.”
Another study from the University of Colorado, published in 2015, reports on-the-ground findings in the aftermath of the West Fork Complex Fire. “Our study is unique because we were actually out in the forest peeling bark off of the burned trees, looking for evidence of the [spruce] beetle,” said Robert Andrus, a graduate researcher and lead author of the study. “We were interested in the ecological effects of the interaction between these two disturbances.”
The researchers collected extensive field data in subalpine forests in the eastern San Juan Mountains of southwestern Colorado “to investigate whether a gray-stage (<5 years from outbreak to time of fire) spruce beetle infestation affected fire severity.” Based on this direct, empirical evidence, Andrus’ team found, “Contrary to the expectation that bark beetle infestation alters subsequent fire severity … analysis revealed no influence of pre-fire spruce beetle severity on nearly all … measurements of fire severity.” They concluded that “higher levels of spruce beetle infestation did not lead to more ecologically severe fires.”
In 2025, a team led by Dominick DellaSala with the Conservation Biology Institute in Oregon notes that beetle-kill logging projects have widespread support by the Forest Service, western governors, and members of Congress as a means of stopping fast-spreading wildfires. But the DellaSala research team determined, “Logging trees that have been damaged or killed by natural disturbances but remain standing” is a “fundamentally flawed” approach to “mitigating fast-moving wildfires.” These catastrophic fires burn “grasslands, shrublands, logging debris, and parched (but still-green) forests under weather anomalies that produce high winds, fuel aridity, and extreme temperatures.” The consensus of relevant research is that the most destructive wildfires have nothing to do with standing dead trees and everything to do with climate and weather conditions, especially wind and drought. Under these circumstances, fires are impossible to extinguish or contain, allowing them to spread into communities, where homes and other buildings become the primary source of fuel.
The comprehensive work by Meigs et al. reinforces the conclusions of other studies and sums up the best available science: “In contrast to common assumptions … we find that insects generally reduce the severity of subsequent wildfires.” In other words, wildfire mitigation is not a legitimate reason to log trees killed by bark beetles and other insects like Western spruce budworm. Officials should not rely on unsupported rationale to propose projects that may actually be counterproductive to the stated goal of mitigating wildfire severity.
Photo: A pine forest experiences a mountain pine beetle outbreak on the Humboldt-Toiyabe National Forest near Reno, Nevada. Logging beetle-kill trees on public lands is a common practice, justified as wildfire mitigation (Forest Service photo).
