Scientists, DEC Wage War Against Emerald Ash Borer; Parasitoid Wasps Released

RANDOLPH – A team of research scientists and entomologists from the SUNY College of Environmental Science and Forestry, the USDA, and the New York State Department of Conservation recently came to Randolph to continue their research on the emerald ash borer.

Dr. Melissa Fierke, associate professor of forest entomology at the SUNY College of Environmental Science and Forestry, said during their three-day investigation, May 12-14, the team cut down a few small trees from the woodlots of local landowners who gave them permission three years ago to conduct scientific studies on their properties. The trees were then cut into 1-meter sections, for sampling, and brought to the Randolph Fire Hall to see if they could find any infestation and/or parasitoids.

In an effort to combat emerald ash borer, the team has released thousands of tiny parasitoid wasps that parasitize EAB larvae – killing them. According to Fierke, they use three different wasps, ranging in size from a grain of rice to half a grain of rice and down to the size of a 12-point-font period.

“The wasps lay their eggs on the EAB larvae and when the wasps’ larvae emerge from their eggs, they parasitize (feed on) the larvae of the ash borer,” she said.

After very slowly and carefully peeling the bark off to expose the EAB larvae, the researchers inspect the wood to see if any of these tiny wasp larvae are feeding on them. Fierke commented that they found lots of emerald ash borer, but only a few parasitoids in the ash samples.

Emerald ash borer, Agrilus planipennis Fairmaire, is a shiny-green destructive Asian beetle – about one half inch long. The adult beetles eat the foliage of ash trees, but cause little damage. The larvae, however, feed on the inner bark of ash trees, disrupting the tree’s ability to transport nutrients down to their roots.

“The beetles come to the United States via wood pallets, boxes and crates, and packing materials on ships from Asia,” Fierke said. “And it’s not a one-way street. They have really horrible pests in Asia that came from here (United States).”

Fierke said New York State DEC’s Division of Lands and Forest deserves accolades for doing what they have done with regards to identifying, finding and trying to slow-down the spread of EAB. She said the Forest Health team from the DEC has been phenomenal and they were working with them in Randolph.

A third set of collaborators includes Dr. Julie Gould, USDA Animal and Plant Health Inspection Service (APHIS), and Dr. Paul D. Manion, a renowned forest pathologist.

“Dr. Gould is one of the gurus of these parasitoids and her expertise is Asian wasps for EAB biocontrol,” Fierke said. “She travels to Asia to find the parasitoids and then she does extensive studies to make sure they only attack EAB and don’t attack our native beetles.”

Dr. Paul D. Manion, of Cazenovia, is a retired professor from the SUNY College of Environmental Science and Forestry (2001). Fierke said he has a passion for eradicating tree diseases and has been assisting the team – out of the goodness of his heart – and has worked with them, in Randolph, every year since the research began.

Fierke said the first discovery of emerald ash borer infestation, in New York state, was found in Randolph in 2009 by Mike Griggs and John Vandenberg, research entomologists with the USDA Agricultural Research Service (ARS), who are also working with the team.

In 2009, Griggs and Vandenberg were driving down the interstate, headed to Michigan to do EAB research, where it was discovered in 2002. They saw dying ash trees by the gas station, in Randolph, and they suspected EAB damage.

According to Fierke, on their drive back from Michigan, they stopped at the same gas station and, as they were looking at the trees, an emerald ash borer actually landed on one of their shirts. At that moment, they were able to confirm that it was EAB. Since then, 11 more spot infestations have been discovered within New York state.

Jerry Carlson, research scientist for DEC’s Division of Lands and Forests, said Randolph is the hot-spot in Cattaraugus County. An additional infestation has been found in the Dunkirk area of Chautauqua County, although the extent hasn’t been fully delimited because it’s difficult to find early attacked trees.

“We use increased woodpecker activity to spot attacked trees and to determine the perimeter of infestation before the trees leaf out,” he said. “The other way of determining the spread is to cut down trees suspected of hosting the pests.”

He said woodpeckers are their primary surveyor because they do a very characteristic “emerald ash borer foraging pattern.” Once the pattern is identified, it’s almost always emerald ash borer. However, the woodpeckers won’t go after a lightly infested tree because there isn’t enough food for them to bother with it.

Vandenberg said some of the bigger infested trees become beetle factories because they have so much living tree-tissue and can produce many more times beetles than smaller trees. He said those trees should be targeted for removal before they keep producing beetles and before they die.

“But that’s the most expensive target to go after,” he said. “To take out the really big trees can be complicated because there are often power lines involved, street traffic and things like that. It’s an impossible task for state agencies because, not just Randolph, but other places around the state have this kind of infestation growing.”

“We’re hopeful the wasps will impact the problem because they’re a much longer-term solution,” Vandenberg continued. “It’ll take a while to get them established and we’d like to have more resources to devote to mass producing these special wasps.”

According to New York Invasive Species Clearinghouse, the emerald ash borer puts all of New York’s 900 million ash trees at risk. Black and green ash are keystone species in wetland ecosystems and their loss could mean the loss of a whole ecosystem. In New York state’s hardwood forests, one in every 10 trees is an ash.

For more information or to report possible infestations, visit the DEC’s website,, where the Emerald Ash Borer Survey Form may be filled out, or call the DEC’s toll-free hotline at 1-866-640-0652.