Tent caterpillars strip aspens above Santa Fe
Despite appearances, forest expert says most trees should grow new leaves this summer
Caterpillars are defoliating aspen groves along N.M. 475, the road to the Santa Fe ski basin, the U.S. Forest Service says, but damage to the trees that form one of the Santa Fe National Forest’s most popular vistas might not be as severe at it appears.
“To the casual observer, the aspens may appear to be dying,” a news release says. “But those bare branches signal the return of the western tent caterpillars, native defoliators whose larvae feed on a variety of hardwood tree species. At least here in New Mexico, they seem to be particularly fond of aspen.”
In most cases, says Forest Service entomologist Andrew Graves, the affected trees will grow new leaves, putting out new shoots over the summer that will appear more bronze than gold in the fall.
“In old trees or trees stressed by disease, the caterpillar can hasten mortality, but most survive this annual harbinger of summer in the southwestern United States,” he said.
Tent caterpillars are a normal part of the forest cycle and periodically set up shop in different portions of forests all over the West.
The caterpillar gets its name from the silken “tent” it builds to protect the larvae during molting, the news release says. As they mature, the larvae disperse and continue feeding on leaves until it’s time to retreat into cocoons for their transformation into moths. The process takes a couple of months, after which the adults mate and the female moths lay eggs that become next year’s caterpillars.
The eggs are massed in small, silver bullet shapes glued to twigs. The larvae hatch but remain inside the egg mass through the winter.
The Forest Service conducts annual aerial surveys over the summer months to track the damage done by western tent caterpillars and other insects in New Mexico’s national forests.
The outbreaks of tent caterpillars go little noticed by humans unless they occur near popular hiking and camping areas.