NISSWA — An overgrown baseball field in northern Minnesota is a peaceful place on a Sunday afternoon, but it’s also a line of defense. Several volunteers armed with nets walk carefully around small, anthill-like burrows, waiting for their targets. 

With a flick of the wrist, a shiny, elegant black wasp falls into the net. With luck, it also drops something else—a shiny beetle. That’s exactly what the Wasp Watchers are looking for.

This is biosurveillance—using one organism to track another. In this case, a native wasp called the smoky winged beetle bandit is helping volunteers locate and document the spread of the highly destructive emerald ash borer beetle.

Since 2014, Jennifer Schultz has run the Wasp Watchers program through the University of Minnesota Extension. She travels to locations all around the state in search of areas where these solitary ground wasps make their burrows. The compacted, sandy soil found on overgrown ball fields is perfect terrain for these nonaggressive, harmless wasps. 

The wasps feed exclusively on the buprestid family of beetles. Most of these beetles are native to Minnesota—except for the emerald ash borer, which attacks live, healthy ash trees. 

“So because emerald ash borer is in the same family as all these other beetles that they natively hunt, if emerald ash borer happened to be here, they would hunt that as well,” Schultz explained. 

The wasps hunt in the treetops, where they locate their prey, paralyze it with venom and carry it back to their underground burrows. Upon capture, a wasp will drop the beetle into the bottom of the net and fly freely away to hunt again. Schultz and the other volunteers then collect the beetles, which they send to a taxonomist for identification before the samples are added to the University of Minnesota collection. When emerald ash borer is present, Wasp Watchers report it to the Minnesota Department of Agriculture. 

Last summer, Wasp Watchers identified emerald ash borer in 10 new locations, where it had never been found before. At one site, volunteers collected emerald ash borer beetles, then went to look at the surrounding trees. There were not any visible signs of emerald ash borer damage—or at least not yet.

“The wasps are actually finding them before the symptoms are appearing on the trees,” Schultz said. “Which is great. With invasive species, the earlier you find it, the more choices you have for management.”

In addition to its function as an early warning system, Schultz sees the Wasp Watchers program as a good way to get people of all ages involved in citizen science in their community. 

“There’s so many great challenges we have ahead of us, with climate change and invasive species, and we don’t all just have to sit idly by and do nothing,” she said. “We can get involved; make a difference. Especially in Minnesota; I feel like people are really great stewards and really want to be involved and want to educate themselves and take action.” 

She especially likes to work with youth groups and families, since it’s a good way to introduce the idea of conservation and invasive species to young people. Schultz’s 11-year-old son Callum tagged along on the trip to Nisswa, where he caught the most beetles of the day. 

“When you go catch the wasps and then you get a beetle, you just feel like you’re helping to find invasive species, and it just feels like you’re helping the environment,” Callum said. 

Earlier this summer, Schultz hosted a few trainings around the Twin Cities metro, visiting parks such as Tolzmann Park in Wyoming, Lino Lakes Elementary School and Marine Elementary School. 

The visit to Nisswa didn’t turn up any emerald ash borer, but Schultz wasn’t surprised. 

“We haven’t found it up in this area yet and hopefully we won’t, but just surveying for it gives us that much more information,” Schultz said. “It’s just another opportunity to be on the lookout for it.” 

Schultz’s wasp trainings are mostly over for this summer, but she encourages those interested in the Wasp Watchers program to contact her. She can be reached at the 612-301-8310 or Learn more about the Wasp Watchers program online at 

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