USDA Biological Control Facility Seeks Ash Trees To Battle Emerald Ash Borer

USDA staff cut a ‘bark window’ in green ash to uncover signs of emerald ash borer.

Emerald ash borer (EAB) is an invasive insect from Asia first introduced into the United States in 2002. Since its discovery, EAB has caused tens of millions of ash trees to die and decline. Today, the U.S. Department of Agriculture (USDA) uses ash trees against the pest to help preserve and protect the tree species. They are asking Wisconsin landowners for their help.

Wisconsin landowners have donated live, infested ash trees to USDA’s EAB biological control program. The staff will then use the wood to cultivate EAB’s natural enemies and release them in Wisconsin and 28 other EAB-infested states. The biocontrol staff will need more ash trees to continue producing and releasing these stingless wasps that attack and kill EAB and are hoping more Wisconsin residents will consider donating their ash trees this year.

Biological control (Biocontrol) helps to reduce pest populations by using natural enemies such as parasitoids (stingless wasps), predators, pathogens, antagonists (to control plant diseases) or competitors. It is a practical option to suppress pest populations and an environmentally sound pest control method.

The stingless wasp (Spathius agrili) lays up to 20 eggs on an emerald ash borer larva. Once the eggs hatch, the wasp larvae will feed on and eventually kill the host.

“Our facility in Brighton, Michigan, is one of a kind,” said Ben Slager, EAB Biocontrol Manager. “We rear almost a million wasps each year and provide them at no cost to our State cooperators for release. We’ve harvested EAB-infested ash in Michigan, Ohio, and last year in Wisconsin. Over the years we have had to travel farther to find the material we need.”

Staff look for live green ash stands where trees range from 8 to 20 inches in diameter and show a significant decline, including cracked or loose bark, dead branches and thinning leaf canopy. They also look for damage from woodpeckers feeding on EAB larva. This season the staff will scout for potential properties in Eastern Wisconsin, ranging from Sheboygan and Fond du Lac counties to Outagamie and Door counties.

“Right now, we are making phone calls to land managers to ask for their help in locating potential sites for harvesting ash trees in the fall,” said Kyle Loughlin, Biocontrol Field Team Leader. “After we get some leads on sites, we’ll visit those locations this summer to determine if they meet the criteria and develop a schedule to begin harvesting sometime in December or January.”

A second wasp species, Tetrastichus planipennisi, lays its eggs inside emerald ash borer larvae where they feed and develop into red-eyed pupae before completing their lifecycle.

Loughlin encourages interested property owners to call him so they can talk about donating their ash trees, and he can answer their questions.

“Many people call me because a neighbor or friend told them what we are doing,” Loughlin said. “I explain how the process works and what they can expect. There’s absolutely no pressure to decide; in fact, I recommend that they take some time to think before they move forward. Even after they decide to donate their trees, they can still change their mind.”

USDA is interested in a minimum donation of 100 green ash trees per harvest site. USDA contractors will harvest trees on weekdays between January and May at no cost to the landowner. To the best of a contractor’s ability, they will return the site to pre-harvest conditions.

Contact kyle.m.loughlin@usda.gov or 734-732-0025 for more information.

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