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Moth outbreak stresses trees in New Mexico forests

ALBUQUERQUE – An insect outbreak is believed to be causing conifer stands in some central New Mexico forests to lose their needles, further stressing trees amid an ongoing drought.

Officials with the Cibola National Forest said Wednesday that Douglas fir, white fir and even some ponderosa pine trees are turning brown as the larvae of the tussock moth feeds on the previous year’s needles.

The concern, officials said, is that defoliation weakens the trees, making them vulnerable to subsequent attacks by bark beetles that may kill the tree tops or even entire trees.

The population of Douglas-fir tussock moths, which are native defoliators, has been increasing in the Sandia and Manzano mountain ranges just east and south of Albuquerque.

“Trees may recover from early infestations which can look quite dramatic. However, multiple seasons of repeated defoliation can predispose trees to disease and other insects causing tree mortality,” Forest Service entomologist Steven Souder said in a statement.

Officials also warned that people should avoid touching or handling the insects.

The caterpillars have thousands of tiny hairs covering their bodies. The female moths, egg masses and cocoons also have hairs that can cause tussockosis, an allergic reaction from direct skin contact with the insects themselves or their airborne hairs.

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

The Forest Service conducts annual aerial surveys during the summer to track damage done by the moths and other insects around New Mexico’s forests.

Souder said trees that regrow their needles will put out new shoots over the summer that will appear more bronze than gold in the fall.

In older trees or trees stressed by drought, the caterpillar can hasten mortality.

While extreme and exceptional drought in New Mexico are less prevalent than last year, all but a small portion of southern New Mexico is dealing with some form of drought. Most of central New Mexico is seeing moderate to severe conditions even as summer rains begin to tapper off.