Can wasps save the ash tree? Native Americans are giving it a try

The Pokagon Band of Potawatomi are fighting emerald ash borers the natural way and hope to preserve a part of their heritage in the process.
Vic Bogosian has an 18,000-strong army--or, rather, air-force--of wasps, and he's looking for more draftees. They're fighting an enemy of the Pokagon Band of Potawatomi, the emerald ash borer, an invasive species from China that has been wiping out an important part of Michigan's Native American culture, the ash tree.

"The bugs here yet?" the Pokagon's natural resources manager asks the front desk of the Pokagon administration building near Dowagiac.

No bugs. He'd been able to place batches of wasps about every-other week since August. But the next expected batch of 3,000 to 4,000 wasps hadn't arrived. Maybe the FedEx guy left the box on the truck, he speculates. Or, there may be no more bugs for the year. "They weren't really clear on when they were winding down production," Bogosian says.

The wasps, also from China, are tiny in size, ranging from fruit fly to mosquito, and stingless, but they have a powerful ability to hunt out borer larvae burrowing under ash bark. The wasps work as "parasitoids." The wasps lay their eggs on the emerald ash borer offspring in the late summer to fall. Over the winter, something out of the movie "Alien" happens, but on a much-smaller scale.

Only one facility, in Brighton, north of Ann Arbor, raises the wasps for the USDA Animal and Plant Health Inspection Service (APHIS). As the borer spread so has demand for the wasps.

First signs of a problem appeared in 2002, in southeast Michigan, as ash trees began dying. Ground zero was likely Detroit, where borers arrived in wood packing materials from China. The larvae of the green beetle tunnels in and feeds on the most-vital part of the ash, the area just under the bark. When an ash is infested, it has about a 95 per cent chance of dying.

A shockwave of emerald ash borers spread out into Canada and through the Midwest. Major infestations have now reached as far as Colorado, Louisiana, and Massachusetts. Some of the spread could have been from the beetles expanding their range, but much was likely from people ignoring quarantine rules by moving infected wood to uninfected areas.

In 2012, the Pokagon band got to work on the problem. "The black ash is very important to the Potawatomi," Bogosian says.

Heritage threatened

"I make all kinds of stuff out of black ash," John Pigeon, Pokagon citizen, and seventh-generation basket maker, says from his home in Moline. His list includes bows, toboggans, cups, bowls, game implements, rattles, and many, many baskets.

His is a heritage that goes back to a time before Europeans arrived in the woods.

What would it feel like, for him, if all the ash of North America were wiped-out? Pigeon puts it in context:

"I learned basket-making from my mom and dad, and they learned it from their moms and dads, and they learned it from their moms and dads. For thousands of years, my family has been making baskets, making all different types of things, from this tree that the people call black ash."

He teaches his children and his grandchildren, and anyone else both inside and outside of the tribe who'll listen. "We try to share our culture so everybody can see the beauty in this."

In every season, for most of his 58 years, Pigeon has gone into the woods. "I gained knowledge and respect of the tree, and I have a relationship with the Earth, especially with those black ash trees that I've been permitted to use through their good graces. I harvest those black ash trees. For me, if that ends, that would be a big part of my life.

"Sometimes, when my son and I have been out in the woods looking for a tree, there have been times when I've not felt as hopeful, and I've actually cried out in the woods to see all the skeletons of those trees that used to be so, so plentiful back in my mom and dad's time. To see them just be decimated, it's a powerful thing. Because I grew up with all of those trees, and for me, they're just like family," he says.

"To see them just go down, it's a sad thing. But I always have hope. Between God and man, we'll come up with a solution. When the Creator puts these things on us, we rise to the occasion."

Trying to achieve equilibrium in the Michigan woods

Bogosian squished on through the damp, bog-like ground in the Pokagon's woods near Rodgers Lake, to the last site of wasp placement.

Black ash thrive around wetlands. Or, they should be thriving. Ash loss in the area has been around 90 per cent, he says. It varies with the species. White ash do better against the emerald ash borer, but green and black ash, "they just take it on the nose.... If we were to walk 100 yards that way, if we were to count the ash, that number would bear out. Most of them had died."

In 2012, the Pokagon took on the problem with pesticide treatments. That works, to a point--each tree must be injected directly with the pesticide every two years, which is not feasible or cheap to do to all their ash.

Bogosian pointed out a short chunk, or "bolt," of ash hanging from a tree. The wasp-raisers at the USDA APHIS Brighton facility first infected the ash that it came from with emerald ash borer larvae. Wasps then laid eggs in the larvae. The bolt is then hung in Pokagon land where wasp larvae will feed on, and eventually burst from, the ash borer larvae.

On the other side of the tree hangs a pill bottle. It contains a paper-like material dotted with wasp-infected emerald ash borer eggs -- another, smaller species of wasp lays its eggs within the eggs. They'll be consumed as the wasp develops.

The two species of Asian wasp will fly out in the spring and infect the emerald ash borers that threaten the Pokagon's remaining ash. The USDA has been working with this process since 2003. They approved the use of the wasps in 2007.

It will be fall of 2016 when Bogosian hopes to see that new generations of wasps have parasitized the emerald ash borer larvae and eggs on their land. It's a process that's about as painfully slow as a presidential election.

The ultimate hope is that the wasps will "push it back to equilibrium." They won't kill all the emerald ash borers, but they will keep them in check enough that the ash can recover. It's been found that in China, nearly 90 per cent of the EAB larvae and eggs are parasitized by the wasps. Bogosian is not sure if it will get to that level. "It's going to take a while to build up."

Could the wasps turn on North American lifeforms and become yet another invasive species?

The USDA has done considerable research and testing on these bugs, he says. "Before a non-native animal gets released, they wanted to make sure there was a very low chance that it would blow up in their faces."

Tests with the wasp began in 2003. Jian J. Duan, research entomologist and lead scientist with the USDA ARS Beneficial Insects Introduction Research Unit, worked on the project and has published papers on the subject. He says the wasps are "very host specific on EAB. It's possible that some of the native beetles (in the same genus as EAB) may be occasionally attacked, but the population impact on these non-target beetles would be minimal."

Duan says that signs are good that the wasps will control the borers. At the first test sites in Lansing, "we have begun to see the impact (on emerald ash borer population) in about seven years." An equilibrium can be achieved to a point where ash can come back, Duan confirms, but "it normally takes at least five to ten years for the wasps to establish large populations to have significant impact on EAB."

Something else to consider: In Michigan, the overall emerald ash borer population has dropped considerably because so many ash are dead, Bogosian says. "They've eaten themselves 90 percent out of house and home at this point. So the beetle population has tumbled since they first got here," he says.

"The best thing to do is to not screw the system up in the first place. But unfortunately, we came to the party after that had already happened," Bogosian says.

Trees and their stories

Pigeon used to go into the woods with his children to plant trees. He does it with his grandkids now.

"I have them take a little stick, poke a hole in the ground, they put the seed in there," he says. "Just so they know it's not all about taking, we have a responsibility to nurture those trees, those things out in the woods, so they could nurture us, so there's a payback. So the trees, the earth out there, can see that we're trying to help."

This spring, he and his grandkids were looking for morels in the Allegan State Forest, where his parents would take him. He remembered that his son, at around 5 years of age, planted seeds in the same area.

He told them, "Hey, you guys, look at this tree right here. It's your uncle, he planted that tree when he was close to your age. Look how big that tree is right now. Your uncle, he didn't make it grow, but he had a place in its placement, where it was going to grow.

"They were proud, looking at the tree. It was still viable," he says. But the trees around it were struggling. "It may have trouble just seeing its family around it being devastated."

Pigeon is not sure that he'll see the ash come back in his lifetime, but he's hopeful. And he's continuing to share his knowledge with his children and grandchildren. "So they'll have the stories behind why we do what we do, so that when those trees come back, and I know that they will, they'll have those stories... People can learn how to make baskets from a book, but they don't know the stories behind them, behind why we do what we do.”

Mark Wedel has been a freelance writer in Southwest Michigan since 1992. He can be reached at
This story is a part of a statewide Invasive Species Community Impact Series edited by Natalie Burg. Support for this series is provided by the Michigan Department of Natural Resources.
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