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Photo courtesy of Eddie Moore of Albuquerque Journal Tussock moth caterpillars climb the side of a camp shelter at Hyde Memorial State Park, in the Sangre de Cristo Mountains in August 2024. Two group shelters were closed that month because of a caterpillar outbreak.

Meet Three Beetles And A MothThat Are Making New Mexico̕s Trees Bare

By CATHY COOK, Albuquerque Journal

Bark beetles are an important part of New Mexico’s forest ecosystems. They typically attack stressed trees, which are then replaced by younger, stronger trees.

Defoliators are insects that eat tree needles or leaves, stripping trees bare of foliage. Defoliated trees can recover in the spring, but severely defoliated trees may become vulnerable to bark beetle attacks.

The western spruce budworm was the most widespread defoliator in New Mexico forests in 2024, active across 249,000 acres. Here are some of the other insects contributing to tree mortality and defoliation:

Ponderosa Pine Bark Beetle

Like other bark beetles, ponderosa pine bark beetles feed on phloem, a vascular tissue that moves food made in the leaves to other parts of the plant. Five species are considered ponderosa pine bark beetles: the southwestern pine beetle, roundheaded pine beetle, red turpentine beetle, pine engraver and six-spined ips.

The red turpentine beetle is the largest bark beetle in North America, according to a ponderosa pine bark beetle guide from the New Mexico Forestry Division.

In 2024, ponderosa pine deaths caused by bark beetles increased from 5,500 acres of forest to 32,000 acres, according to the New Mexico Forest Health Conditions report.

Douglas-fir Tussock Moth

In its adult form, the Douglas-fir tussock moth is a nondescript gray or brown. As a caterpillar, however, it features distinctive white tufts and bright red spots.

The caterpillar was responsible for defoliating 18,000 acres of mixed conifer forests in New Mexico in 2024, according to the report — a significant jump from 2023, when it defoliated 2,600 acres.

Mixed Conifer Bark Beetles

Two types of mixed conifer bark beetles are found in New Mexico: the Douglas-fir beetle and the fir engraver. These beetles were active in 2024, causing significant tree mortality, particularly near 2022 wildfire burn scars.
Douglas-fir beetles contributed to tree mortality across 13,500 acres, according to the report.

Spruce Beetle

In 2024, spruce beetles — dark brown or black insects — were linked to Engelmann spruce deaths across 9,900 acres of high-elevation forests in New Mexico, a 20% decrease from 2023.

Many of the tree deaths occurred on national forest land in the Santa Fe and Carson forests.
Spruce beetles prefer to inhabit large-diameter Engelmann spruce stands at high elevations, according to the report. The number of these stands has decreased significantly because of spruce beetle attacks and wildfires.

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