Minnewaska State Park will be closed to the public tomorrow, Friday, May 17 due to treatments for spongy moth infestation. The park is slated to reopen on Saturday, May 18.
The spongy moth is a non-native insect from France. The caterpillars are known to feed on the leaves of a large variety of trees. Oak is their preferred species, but they will feast on other trees when oak is not available to them or their numbers are in great excess.
According to Minnewaska State Park Superintendent Eric Humphries, he and his park staff have been actively monitoring spongy moth impacts on trees and recently identified egg-mass counts this winter that would indicate a dangerously high population this spring.
“Spongy moth populations are known to surge periodically before dying back to a less destructive level,” said Humphries.” Trees risk dying if they are exposed to consecutive years of defoliation due to these periodic surges of hungry caterpillars. The timing of our treatment this month is based upon the effectiveness of the treatment relative to the life cycle of the caterpillars.”
When populations are very high or when oak and preferred trees are limited, the spongy moths will eat evergreen species like hemlock, pine and spruce which do not regrow leaves as easily as deciduous trees and can die as a result of complete defoliation. The hemlock trees are already under great threat in the Shawangunk Ridge area where Minnewaska State Park resides.
The spray being used at the park is BKT, which, according to Humphries is “a naturally occurring bacteria found in soils that impacts the caterpillar’s digestive track. There is no risk to humans or pets.” The park superintendent explained that “BTK is the safest and most selective method for reducing the number of caterpillars and protecting the foliage of host trees. It is an environmentally friendly alternative to chemical pesticides and has been used in the US since the 1960’s.” He added that the bacteria is typically broken down within three to five days by sunlight and other microbes.
The BTK treatment is planned for 960 acres of the “core areas of Minnewaska,” said Humphries. “Additional treatments are occurring this spring at Bear Mountain and Harriman state parks.”
Altogether, the office of NYS Parks, Recreation and Historic Preservation plans on spraying 2807 acres with two applications of BTK spaced three to seven days apart.
“Timing is critical for the success of the treatment as we need the right weather window while the caterpillars are still relatively small to be successful,” Humphries said. “Without treatment, the mature oaks risk dying which would create major safety concerns for visitors, as well as negatively impacting the landscape and habitat. We have found that trees weakened by defoliation are more susceptible to other stressors, such as drought, and may die several years after a defoliation event. This treatment is a pre-emptive move to protect tree health, focused on areas of high public use.”
While this treatment has been used to try and reduce the negative impacts of spongy moth populations within the Palisades region and other national and state parks, this is the first time the treatment has been applied at the 23,000-acre Minnewaska State Park Preserve.
Humphries was quick to point out that they have conducted outreach with neighboring private parcels. With the exception of the Shawangunk Gateway Campground, Humphries said that “no other treatment areas are adjacent to private properties,” and that the plan is to “treat our Sam’s Point Area at daybreak to provide this area as an option for visitors to be able to hike the loop road and ice cave trails only while the remaining areas within Minnewaska have treatments finished.”
The park’s goal is to have the treatments finished by later afternoon on Friday, May 17 and to reopen the park back to visitors on Saturday, May 18th. “This is all largely weather dependent and may be delayed,” he cautioned.
“I want to thank everyone for their cooperation and understanding of this important operation.”
Visitors are encouraged to call the park at 845-255-0752 (ext 0) to check on the park’s status.
Join the family! 
