Douglas-Fir Tussock Moths Reemerge Near Taos

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If you’ve driven the High Road to Taos lately, you might’ve noticed a change between Pot Creek, N.M., and U.S. Hill. Hundreds of trees are brown or looking dead. You’ll see them atop ridges, directly along the highway and, of course, if you step deeper into the forest.

This is the result of a Douglas-fir tussock moth outbreak that was first observed in 2024, with entomologists noting their reemergence in late May 2025. It’s a native insect, essentially doing its thing, but there are safety concerns when you're around them.

Below we’ll cover the basics, important safety information and more.

It Looks Quite Dramatic

“This can look drastic,” said Andy Graves, a New Mexico-based entomologist with the Forest Service, who last year explained that we’re witnessing a natural disturbance event in real-time.

“We are observing these outbreaks on the Carson National Forest and across several other national forests in New Mexico due to the right climatic conditions coupled with stands densely composed of susceptible tree species,” he said.

In its larval, or caterpillar, stage, the moths feed upon Douglas-fir and white fir trees. The outbreak is occurring in a dry mixed conifer vegetation community, where fire was historically frequent, thinning out the forest below the canopy.

Historically, many of these forest stands would have much fewer white fir due to frequent fire activity, and outbreaks of the Douglas-fir tussock moth would have been small and isolated to pockets. Due to the much greater amounts of white fir, the outbreaks we are seeing are larger and more dramatic.

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Will the Trees Die?

There are some ifs and buts about the fate of the trees. Defoliation is when the leaves—needles in this case—are eaten by the moths during their larva, or caterpillar, stage. At first, when they’ve just hatched and are small, they eat around the margins of the leaves, causing needles to curl and redden before falling off.

Once all or most of the needles drop, the tree will look dead, which might not be the case. A tree defoliated this year can regrow its needles next year, but defoliation makes it vulnerable to bark beetles and other diseases. In general, if a tree is 95 percent defoliated, it likely will die. The same goes if the tree is defoliated multiple years in a row. With some of these outbreaks being in areas planned for restoration, it presents an opportunity to evaluate and remove trees that die from the outbreak.

How Long Will This Last?

Outbreaks typically last one to four years, however some have lasted up to seven years in New Mexico. Outbreaks are not uncommon in New Mexico’s national forests, including the Carson National Forest, often reoccurring in the same canyons and areas. The surge of moths will attract predators, such as birds, parasitic flies, spiders, and ants, all which can act as natural control agents. Other natural controls include spring frosts, parasites, pathogenic microbes, lack of food, and—most often—a virus that can abruptly collapse an outbreak population.

In May 2025, an entomologist visiting the area suspects a virus fatal to the moths, called nuclear polyhedrosis virus, might be starting to take hold in the local population. This often occurs when the population becomes so dense that it easily spreads between larvae, ultimately halting a localized outbreak of moths.

What About the Wildfire Risk?

The risk of a wildfire is always there, regardless of an outbreak. When it comes to the affected trees contributing to a wildfire’s spread, we must look at their susceptibility to ignition. Here are the three main scenarios:

• A tree is at its most flammable when red needles are still on its branches. The dried needles act as fine fuels that are more susceptible to ignition and can carry a fire up to or keep it in the canopy. When a wildfire reaches a dense canopy, it can spread with ease from tree to tree, killing trees along the way. However, this stage does not last long, and visitors will notice the needles will fall off quickly with summer rains.
• Green needles have moisture content, but they can still ignite and contribute to the spread of a fire, thanks to a class of flammable natural chemical products called terpenes. Think about that fresh pine scent from the needles and resin oozing out of the bark. Those come from terpenes, and they are also found throughout our modern-day life (think turpentine, wood stain and even cosmetics, to name just a few).
• When a tree is completely defoliated and dead, it’s referred to as a gray tree. It’s contribution to the fire ignition and spread is minimal. In fact, there is evidence that fire risk is reduced after an insect outbreak. That’s not to say it won’t burn, but it doesn’t pose a greater risk than a green forest because its branches and trunk will not as easily ignite like needles. The fuel of the trees is still there and can change fire behavior should a fire go through the affected area.

To sum it up, there is a heightened risk of wildfire spread in the short term while the red needles cling to branches. As they drop, the affected trees’ contribution to spread is reduced.

In the long-term, the area will still need fire in the understory. After all, it is a frequent fire vegetation community.

As it happens, some of the outbreak is occurring within the McGaffey Forest and Rio Grande del Rancho Watershed Restoration Project, which seeks to address the overall forest health and resiliency within a 30,000-acre area. More details on project work—thinning and prescribed fire—are forthcoming.

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Are the Moths Dangerous to Me?

They certainly can be! So be wary when around them.

An allergic reaction called tussockosis can occur from direct contact with the hairs of the caterpillars, which has thousands of them. And those hairs can go airborne, unseen to the eye. Hairs are also found on female moths, egg masses, and cocoons.

Tussockosis severity may vary between individuals, by the amount of exposure, and the level of the outbreak.

Symptoms may include itchiness, skin rashes, skin irritation, watery eyes, runny nose, and sneezing. More severe reactions, though less common, include blisters, coughing, shortness of breath, wheezing, and chest tightness.

If contact does occur, immediately wash the area of exposure. If symptoms become severe or problematic, immediately seek medical care.

Can You Share More Location Details?

Besides the Highway 518 corridor, visitors on a handful of connecting forest roads may see or drive directly through outbreak areas. They include forest roads 114 (Picuris Lo), 115a and 115b (both unnamed), 439 (Little Rio Grande), 440 (Maestas Park), 442 (Gallegos), 469 (Telephone Canyon) and 476 (unnamed).

Some areas are farther out and away from roads, including Fernando Mountain, Rio Osha and Cañon Bilbao.

Another outbreak, primarily on private lands in El Salto, began in 2023. About 58 acres were affected along the forest boundary west of the Latir Peaks Wilderness, where activity continues this year.

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How Do You Know About All These Locations?

By plane, by vehicle, and by foot! The Forest Service’s State, Private, and Tribal Forestry organization conducts forest health monitoring across national forests and adjacent lands, regardless of ownership, across the country.

Staff surveyed 3.9 million acres in and around the Carson National Forest, primarily by air, between late June and late July. They identified about 3,000 acres of Douglas-fir tussock moth outbreaks on the forest, along with other insect and disease activity. Western spruce budworm is the most prevalent defoliating insect, but it causes much more reduced levels of defoliation that can cause long-term damage over many years in some places.

The Forest Health surveys are conducted annually and these outbreak areas will continued to be monitored.

Can I Collect Fuelwood?

If it’s within the terms of a dead and down fuelwood permit, then yes! Please keep in mind the above safety considerations.

What if I Think Moths are on My Property?

If you’re in Taos County, contact the Taos Soil and Water Conservation District. They can send a forester to your property for an assessment and provide recommendations on actions and sources for assistance.

I Want to Learn More

Let’s dive in! Here are some good resources to check out:

• The Forest Insect & Disease Leaflet for Douglas-fir tussock moths contains a comprehensive scientific overview of the insect, its life cycle and much more.
• “The Very Prickly Caterpillar: Navigating Douglas-fir Tussock Moth Outbreaks” tells the story of one Forest Service researchers work on the insect.
• In November 2023, the Taos News covered an outbreak on private lands in El Salto.