Efforts underway to save oak trees from spongy moths across Pennsylvania

If you are wondering why you haven’t been finding as many acorns under oak trees, spongy moths may be to blame.

Spongy moths, formerly called gypsy moths, have been eating oak tree leaves across the state since 1970. Last summer was a devastating year for parts of the state.

“In 2022 were some of the highest numbers of (spongy moth) population in the central part of the state that I’ve ever seen,” Paul Weiss, Pennsylvania Game Commission chief forester, said. He's been involved in spraying spongy moths for about the last 15 years while working in a variety of state positions.

This year, he feels the numbers have coalesced in the central part of the state and shifted east.

“The numbers are still damagingly high as far as egg mass counts, but they are lower than last year,” he said.

The Pennsylvania Department of Conservation and Natural Resources is spraying about 300,000 acres of state lands for the small insects and the Game Commission is planning to spray nearly 110,000 acres of state game lands this spring.

“This year is the largest spray program the Game Commission has ever undertaken. We’re just under 110,000 acres we’re looking to spray this year, so we’ve never sprayed that many any other year,” Weiss said. Last year the agency sprayed 63,000 acres by airplane which was, at the time, the highest number of acres for one year.

The Game Commission’s spraying will occur throughout May in the following regions: southcentral, 1,323 acres; northcentral, 94,788 acres, southeast, 3,107 acres, southwest, 226 acres and northeast, 9,736 acres. The agency reports the northwest region had spraying last year, but the spongy moth population there seems to be in decline and, as such, no spraying is scheduled in that region.

Weiss said the goal is to protect the habitat that many animals depend on each year. Critters from chipmunks, squirrels, turkey, grouse, deer and bear look for acorns each fall to help them survive.

“Pretty much the entire food chain of mammals relies on acorns,” he said including small critters like the wood rat.

“For the Game Commission’s perspective, the biggest reason we invest the amount of money that we do into this program and the time, has nothing to do with the timber resource. We’re trying to maintain the maturity of the oak and the oak mast capacity that the oak provides for the habitat perspective," he said.

In the northern tier of Pennsylvania in 2022, there were large swaths of public land that didn’t have acorns last year because of the spongy moths.

“The acorn crop was nonexistent,” he said. When that happens the animals move to areas like hickory tree stands to find food. “They have to go to where the food is.”

The moths prefer the chestnut and white oaks, but they will eat red oak leaves and other tree leaves, too.

“I’ve seen them already go down to eating blueberries,” he said.

Over the years, there has been a significant loss of oak trees, he said. During the last major outbreak between 2006-2009, there were tens of thousands of acres of oak forests across state forest land, state game land and private ownership of heavy oak mortality, he said. The oak died uncontrolled, and many of those places grew back in birch and maple stands, which have significantly less value to wildlife.

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The trees that were defoliated to the point where the tree died will be noticeable the following year when they don’t have leaves. Landowners will be harvesting those oak trees because they don’t want to lose out on the timber value of the quality lumber species. If the trees survive, he said they may need up to a decade to recover and start producing acorns again.

He blames a soil-based fungus that has caused the cycle for gypsy moths to plateau and extend out.

“There are long gaps in between infestations but when they do come back, they seem to be pretty damaging when they come," he said.

For people who own large numbers of trees, he said there are several private application companies that can do spraying. The cost can range from $30 to $50 an acre to spray what’s being used by the state. “They are not necessarily cheap, but they are not cost prohibitive given the fact that you are looking at your oak trees as a timber resource,” he said.

“If you are looking at your woodlot as your little corner of paradise, your wildlife habitat where you hunt, being able to keep those oak trees healthy and maintaining the potential for an acorn crop, some people would say there’s no price they wouldn’t put on that,” Weiss said.

Brian Whipkey is the outdoors columnist for USA TODAY Network sites in Pennsylvania. Contact him at bwhipkey@gannett.com and sign up for our weekly Go Outdoors PA newsletter email on this website's homepage under your login name. Follow him on Facebook @whipkeyoutdoors ,Twitter @whipkeyoutdoors and Instagram at whipkeyoutdoors.

This article originally appeared on Erie Times-News: Spongy, gypsy moth spraying program in Pennsylvania