On the east side of Langton Lake Park in Roseville, Minn., Zach Pollei's giant ash trees are marked with warning signs by the city.
"All I know is that it's cutting off the water supply and they'll go down in time," Pollei said.
The water supply is being cut-off by the return of the emerald ash borer infestation.
Mark Abrahamson with the Minnesota Department of Agriculture pointed to the serpentine pattern left by EAB, and he cut away the bark of one tree to show more troubling developments.
"This is the pupa," he said. "Doesn't look like much but this is turning into a beetle right now."
Abrahamson said at least 100 ash trees in Roseville are infested with emerald ash borer and the trees are dying.
"When they're killed they become dangerous because the branches can drop off and fall, so if there is a path or anything else they can fall on then it's a hazard," he said.
So there's now a race to cut down and get rid of these infected trees before the hot summer months arrive, when these bugs usually start coming out of hiding.
"What we're really concerned about is finding several new locations that previously haven't had emerald ash borer to implement management programs to help it from spreading," Abrahamson said.
From the field to the lab, Rob Venette with the U.S. Forest Service is studying ways to stop this infestation, saying it's the worst he's seen since 2009 when the bugs were first spotted in Minnesota. But there are signs the infestation is slowing down.
"We found it very early," he said. "Homeowners are being conscientious and not moving things around. They're being aggressive, cities are removing infested trees."
In the metro, Hennepin and Ramsey counties are already under quarantine and there's a national and local ad campaign asking people not to transport firewood.
For now, Zach Pollei is trying to figure out how to slow down the infestation in his trees, but it's likely too late.
"I'm sure we'll have to spend money to spray or do whatever we'll have to do," he said.
Most cities are responsible for removing trees on public property, but homeowners have to do the rest.