Unwanted pests set up camp

By Robert Nott
The New Mexican
Posted 6/10/20

Their long, silken, almost delicate tentlike structures fool an onlooker into thinking all is benign. It isn't. The western tent caterpillar is the enemy - at least to …

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Unwanted pests set up camp


Their long, silken, almost delicate tentlike structures fool an onlooker into thinking all is benign. It isn't. The western tent caterpillar is the enemy - at least to the beautiful leaves of aspen trees.

The insect is back in the area, and though entomologists say they aren't deadly to aspens, they will denude foliage quickly.

"It looks bad, once they are done, but they will be done eating pretty soon," said Scott Bundy, a professor of entomology at New Mexico State University in Las Cruces. "After that, the plants will recover. It will usually look bad for a couple of months, and if people can deal with it for that long, the plant will start regrowing leaves. It usually does not lead to much of a health impact on the tree."

Nor do the caterpillar's tents harm the trees. Once insects move on to lay eggs and mature and become moths, the tents slowly erode.

The good news is that the caterpillars arrive in the spring and early summer and then pretty much disappear for a year - leaving the autumn colors without crawling, voracious pests.

Bundy said the caterpillars, upon hatching, begin banding together as a communal group to construct the tent, spinning silk out of their mouths. The tent protects them from both inclement weather and predators, such as birds, that eat the caterpillars. It also serves to protect larvae during molting.

The caterpillars tend to spend most of the hot days in those tents, emerging around dusk to start feeding on trees. In the dark, Bundy said, they release a pheromone trail behind them to lead them back to their communal bed.

After a couple of months, they start leaving the tent one by one, encasing themselves in their own cocoons and then emerging as moths. After they mate, the female lays her eggs and then almost immediately dies.

The male follows suit shortly thereafter.

Ricardo Leon, recreation and lands staff officer of the west zone of the Carson National Forest said that western tent caterpillars have started defoliating aspen and building tents around the Hopewell Lake area, but not as bad compared to other years. Leon said he also has noticed more western tent caterpillar building tents on mountain mahogany compared to previous years, along State Highway 522 in between San Cristobal and Questa.

Leon said the caterpillars have a positive role in the forests. "Western tent caterpillars provide a food source for animals such as birds. Also, when western tent caterpillars defoliated trees such as aspen, this allows more sunlight to the understory vegetation," he said in an email. "In some cases, I have noticed that tent caterpillars have [contributed] to aspen regenerating to more healthier stands of aspen.

Bundy and other bug experts say that if you want to remove the tent from a tree, do not use chemical products, as they can damage the tree. Some experts advise to put the entire tent in a big bucket of soapy water, which will kill the caterpillars.

Bundy said you also could put the tent in your freezer. That'll kill them for sure, he said.

But he added that the caterpillars do serve as protein for predators, and their fecal matter can provide trees with nitrogen.

If you want to salvage the tent and caterpillars but get them out of your backyard, he jokingly suggested you take down the tent and deposit it "in the yard of a neighbor you don't like."

This story first published in the Santa Fe New Mexican, a sibling publication of Taos News. Taos News contributed to this report.


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