The emerald ash borer has marched a little farther north in Minnesota.
The state's Department of Agriculture announced Thursday that Chisago County has become the ninth Minnesota county to be infested by the pest.
Samples have been forwarded to federal labs and Minnesota's Ag Department expects confirmation from the USDA early next week.
Thursday's news means Chisago is likely to join the other Minnesota counties that have been put under an emergency quarantine. The main way emerald ash borers spread to new areas is in firewood, experts say. The quarantine prohibits moving firewood out of an infested county.
Minnesota has a lot to lose to the pest. Its 1 billion ash trees outnumber those in any other state, the agriculture department says. Nationwide, the borers have killed tens of millions of ash trees in two dozen states.
Mark Abrahamson, an entomologist with the state Department of Agriculture, tells MPR News the bug's spread is "kind of inevitable" and suggests it may be reaching a tipping point in Minnesota.
"We're reaching a period where it may start to build and spread more quickly, and that's something that has been seen repeatedly in places where emerald ash borer has been found," he says.