IDL specialist to Sandpoint council: spongy moth detection ‘very unlikely to result in any problem’

By Zach Hagadone
Reader Staff

While the detection of spongy moth in Sandpoint recently raised concerns for some, a specialist with the Idaho Department of Lands told the Sandpoint City Council at its Nov. 6 meeting that there’s nothing to worry about yet.

“We don’t anticipate this to be a huge problem,” said IDL Forest Health Specialist Erika Eidson, who works as an entomologist. 

“The detection is very unlikely to result in any problems because it was detected so early,” she added later.

A spongy moth monitoring trap in Sandpoint. Officials ask that residents leave the traps alone and call the number listed on the traps with any questions or concerns. Photo by the Idaho Department of Lands.

Eidson gave a presentation to the council, in which she said that a single male specimen of the insect — formerly known as the “gypsy moth” — was captured in September at a location near the corner of Oak Street and Division Avenue. It was the first spongy moth detected in the area since the period from 1986-1990, and the insect was considered to be eradicated locally in 1991.

Regardless, IDL will begin expanded trapping efforts around the detection site in 2025, “to see if there are any more moths in the area or if this was just a one-off hitchhiker, which we believe it was,” Eidon said.

Native to Europe, spongy moth is an invasive pest in the Northeast and mid-Atlantic states, where the insect was released by an amateur entomologist in the 1860s in a failed attempt at establishing silk production. Spongy moth do not spin silk, but their caterpillars do feed on broadleaf trees such as oak, causing millions of dollars of damage in areas they’ve infested.

While the species is concentrated in the eastern U.S., it can and does leave that region on firewood, RVs and campers, furniture or anything else that people travel with — which Eidon said IDL suspects is what occurred with the specimen found in Sandpoint.

To confirm that, the department will install 36 traps per square mile in the four-square-mile area of the initial capture, with placement in the summer and evaluation in the fall of 2025. The traps are green in color and armed with a sticky interior and a pheromone lure meant to attract males. The traps are designed specifically to attract males so they don’t inadvertently invite potentially reproducing females from other areas.

IDL, the U.S. Forest Service and Idaho Department of Agriculture have a longstanding spongy moth trapping program that dates back to the 1970s, with nearly 3,500 traps around the state.

“IDL’s monitoring plan has worked,” Eidson said, later adding, “It’s very unlikely that there’s an infestation that’s been happening any longer than this year.” 

For more information or to ask questions about the spongy moth and trapping operations, contact the IDL Forest Health team at 208-769-1525 or [email protected].