WEST GREENWICH — Call it the invasion of the caterpillars.

Thousands of these tiny, fuzzy spotted insects swarmed the tree trunks, branches and grass fields along the western stretches of Plain Meeting House Road.

The forest tent caterpillars, roughly the size of a mascara wand, denuded dozens of oak trees of their leaves. They writhed across the ground and crawled up and down the wooden walls and stone foundation of West Greenwich Baptist Church.

The popping noise in the background? It’s the caterpillars, munching and falling.

The outbreak is a naturally occurring incident that happens every 8 to 10 years, said Bruce Payton, a supervising forester for the state Department of Environmental Management.

The caterpillars were also seen in western parts of Coventry, near the villages of Greene and Hopkins Hollow, and sections of Scituate. Payton said it was not as bad as the portions of West Greenwich by Hazard and Plain roads. About 50 people called the DEM to report the problem.

It is unclear how many acres of trees have been damaged. Payton said some trees have been completely defoliated and he will conduct an aerial survey next week.

The forest tent caterpillars are not dangerous to humans, although they can cause a rash. Payton hopes the caterpillars will run out of food and a natural pathogen, nucleopolyhedrosis virus, will set in to kill off the insects. Already, he has noticed some caterpillars wilting on the trees, a sign that the disease is spreading.

The trees will refoliate, but it could take more than a month, depending on how much rain they get, Payton said.

However, another problematic insect, the gypsy moth, is just starting to come out. The gypsy moth caterpillars are currently very small, about a quarter of an inch, with a silky thread.

The gypsy moth, an invasive species known for defoliating trees, becomes active in late June and early July. Last year, more than 8,000 acres were deforested by gypsy moths, mostly oak trees, Payton said. The hardest hit sections were near the Scituate Reservoir and Coventry, with pockets in Tiverton.

Payton advised homeowners to hire licensed pesticide applicators to treat for gypsy moths now.

Forest tent caterpillars are common and can be found throughout the United States and Canada, according to a U.S. Department of Agriculture fact sheet. The insects prefer broad leaf trees, as well as birch, cherry and ash trees.

While forest tent caterpillars do not spin a “tent,” they form silken mats where they rest during molting periods. Five to six weeks after hatching, they spin yellow silk cocoons, turn into moths, then die after a few days.

David Schwartz, an arborist based in Cranston, said he was surprised by the magnitude of the forest tent caterpillar outbreak.

The best time to combat forest tent caterpillars is once they start hatching. He also suggested homeowners hire an arborist to deal with the trees and to hire a licensed applicator to use the lowest toxic pesticide on the property. If the caterpillars go indoors, hire an exterminator.

Residents living in the leafless portions of Plain Meeting House Road have not fared well.

Stacey Bowes, a customer relations representative, noticed the massive migration to her house last week when the caterpillars ate dozens of oak leaves in the forest across the street, then moved to her property.

For six years, Bowes has lived at 741 Plain Meeting House Rd., the town’s original one-room schoolhouse, built in 1878. She never had such a large insect problem. The only thing that compares, she said, was a huge infestation of gypsy moths that hit her former home in Coventry during the 1980s.

“It’s ridiculous. It’s awful,” she said as she pointed to the caterpillars in her driveway, the lawn and trees. “That’s a rose of Sharon, beautiful, burning bush, Japanese maple. Won’t touch it.”

What the caterpillars did love were her three oak trees and one cherry tree, stripping them to the bare branches. The insects also liked to climb the walls of the swimming pool, still covered, and the unattached screen-covered backyard porch.

The family used to eat their meals in the porch, but Bowes’ son, Nicola Boyd, 15, said “not right now. We won’t even try. I lost my appetite.”

Holly Stephenson, who lives down the road, also had to suspend outdoor summer fun because of the caterpillars.

The outdoor swing set and slide had gone unused. The insects can also be seen all along the front steps and driveway as well. The oak trees surrounding her house and two acres behind the home, where they like to hike, are bare.

“We can’t rake the leaves. We can’t mow the lawn. The kids don’t want to be outside. It’s awful,” said Stephenson, a stay-at-home mother of two. “They drop from the trees, even walking to the bus. They fall on you.”

Instead of playing in the backyard, Stephenson keeps her children indoors or takes them to the town playground.

Stephenson said her family always checks their clothing whenever they enter and exit the house. She also said she will have to get the house “power-washed” because the caterpillars leave droppings everywhere.

“We like to go hiking, too, but that’s not happing at this point,” she said. “Hopefully, this will go away soon.”

To learn more about the forest tent caterpillar, visit the U.S. Department of Agriculture Web site at www.na.fs.fed.us/spfo/pubs/fidls/ftc/tentcat.htm.

Michelle J. Lee is a fellow with the Metcalf Institute for Marine and Environmental Reporting.

mlee@projo.com